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High entropy alloy formation derived from high entropy oxide: unlocking the active sites for green methanol production from CO<sub>2</sub>
No full textIn pursuit of novel materials for CO2 conversion to value-added chemicals, previous research has predominantly focused on copper-based, indium oxide (In2O3)-based, and alloy or intermetallic materials. However, a groundbreaking approach is presented by introducing a high-entropy-based material for CO2 reduction to methanol (CH3OH). This method offers scalability and simplicity, making it feasible for large-scale production of high-entropy-alloys (HEAs). The formation of HEA is facilitated by the presence of Fe, leads to the creation of a high-entropy oxide (HEO) during calcination. Through X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS), comprehensively analyzed the oxidation states and coordination environments of all metals in both HEO and HEA. The formation of Fe3O4 within the HEO structure is evident, with each metal occupying either tetrahedral (Td) or octahedral (Oh) sites. The HEA formed shows exceptional CO2 conversion efficiency and higher CH3OH selectivity. Isolated sites of Co, Ni with Fe, Cu, and Zn, along with CuZn pair, are considered as the active sites for CO2 to CH3OH and further determined by DFT calculations. The altered reaction mechanism upon HEA formation compared to individual metals is investigated using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Finally, Life-cycle assessment (LCA) indicates the carbon-negative footprint
Solar-fuel production by photodriven CO<sub>2</sub> reduction: facts, challenges, and recommendations
No full textSolar fuel production via CO2 mitigation offers a potential approach for solving global energy demand. It is gaining much attention because of its sustainability and environmental friendliness. However, significant challenges remain in this field, including low efficiency, poor selectivity, and large-scale implementations. Despite the recent advancements in the field, optimizing photocatalysts, improving reaction pathways, and scaling up processes are the key obstacles. This Perspective focuses on a holistic approach to the current state of solar fuel production, highlights the challenges that hinder progress, and discusses several branches of solar fuel production that have emerged in light of the current obstacles. It critically surveys the recent literature and provides recommendations for future research on improving existing processes. Ultimately, we discuss scalable approaches for realizing large-scale solar fuel production and also describe the current policies and networks established to support the development of solar fuel technology for widespread implementation
Demonstration of two qubit entangling gates in a 2D ring resonator based coupler architecture
No full textWe report entangling two-qubit experiments implemented in a novel ring resonator architecture in 2D planar geometry. The ring resonator acts as a multi-path coupler between qubits and can provide beyond nearest neighbour interactions. We demonstrate pairwise coupling between three fixed-frequency transmon qubits connected to the ring resonator with measured coupling strengths (4.70 MHz, 2.80 MHz, and 2.65 MHz) in good agreement with those predicted from finite-element simulations. We implement an all-microwave controlled phase (CPHASE) gate between a pair of qubits with a gate time of 196 ns and demonstrate a two-qubit Bell state with a measured state fidelity of F = 0.88. Our results demonstrate the ability to entangle two qubits using the ring resonator and pave the way for creating highly connected multi-qubit networks in this architecture
Nonlinear Optical Properties of 0D Chiral Hybrid Bismuth Iodides
No full textChiral hybrid metal halides show great promise for nonlinear optical (NLO) applications like circularly polarized second harmonic generation (SHG). The inherent toxicity of lead is a concern for the widespread adoption of frequently explored lead-based chiral hybrid halides. Here, we report the second and third-order NLO properties of lead-free 0D chiral compounds, (R-/S-MBA)4Bi2I10, and their achiral counterpart, (Rac-MBA)4Bi2I10 (MBA: methylbenzylammonium) under excitation wavelength ranging 1360–1590 nm. Chiral (R-/S-MBA)4Bi2I10 exhibits strong SHG along with stronger third harmonic generation (THG). The chiral crystals showed high sensitivity to the handedness of circularly polarized pump light (gSHG − CD ≈ 9% at 1510 nm). The THG response shows resonance enhancement matching the excitonic absorption. Achiral (Rac-MBA)4Bi2I10 exhibits the maximum THG response (χ(3) = 1.05 × 10⁻¹⁸ m2 V−2). Z-scan measurements with non-resonant femtosecond pulse excitation at 800 nm yield high nonlinear absorption coefficients (β) and nonlinear refractive index (n2) for all three samples, with (Rac-MBA)4Bi2I10 exhibiting the highest values. These hybrid chiral metal halides, with efficient second and third-order nonlinearity, and high optical stability, are potential candidates for NLO applications such as Kerr-based optical switching, circularly polarized up-conversion, and communication
Inter-linkage among climate, terrestrial and marine systems: sustainable development perspectives
No full textThe interplay between Earth observation technologies and sustainable development has become increasingly important in addressing global challenges such as climate change, food security, and biodiversity loss. The studies included in this volume explore diverse dimensions of how remote sensing, GIS, and other geospatial technologies are transforming agriculture, water management, and ecosystem conservation. In agriculture, advanced monitoring techniques empower farmers to optimize crop management and enhance resilience against climate variability, while integrated approaches like agroforestry promote biodiversity and sustainable land use. The efficacy of water resource management is enhanced manifold through geospatial insights, addressing the complexities of hydroclimatic extremes and adaptive strategies necessary for coping with climate impacts. Furthermore, the intricate relationships between biodiversity and ecosystem health underscore the need for effective conservation practices, particularly in sensitive regions such as high-altitude wetlands and forest ecosystems. The sections dedicated to ocean and atmosphere dynamics further illustrate how global climate patterns influence terrestrial systems, necessitating a multifaceted approach to climate adaptation and mitigation. Taken together, these contributions highlight the critical role of Earth observation in promoting sustainable development and underscore the need for collaborative science and policy efforts to address the pressing environmental challenges of our time
PARP1-Dependent and Independent Pathways for Resolution of Trapped Topoisomerase I Covalent Complexes
No full textTopoisomerase I (Top1) alleviates DNA supercoiling during replication and transcription, but its catalytic cycle can be hijacked by chemotherapeutic agents such as camptothecin (CPT), stabilizing Top1-DNA covalent complexes (Top1cc) that threaten genome integrity. Efficient resolution of these trapped intermediates is crucial to prevent replication stress, DNA breaks, and cell death. Poly (ADP-ribose) polymerase 1 (PARP1) is a key sensor of Top1cc, facilitating repair by recruiting tyrosyl-DNA phosphodiesterase 1 (TDP1) and modifying chromatin to promote lesion accessibility. Beyond this canonical pathway, emerging evidence highlights PARP1-independent mechanisms such as endo nucleolytic cleavage, proteolytic degradation of Top1 and replication-associated processing. Intriguingly, PARP1 appears to act as a molecular switch between TDP1 and the endonuclease pathway for the repair of Top1cc. This review highlights mechanisms of PARP1-dependent and -independent Top1cc repair pathways, their interplay and redundancy, and how their targeting can enhance Top1-based cancer therapies and overcome resistance
Topside Low‐Latitude Ionospheric Response to the 10–11 May 2024 Super Geomagnetic Storm as Observed by Swarm: The Strongest Storm‐Time Super‐Fountain During the Swarm Era?
No full textThe current study explores how the topside equatorial and low-latitude ionosphere responded to the super geomagnetic storm on 10–11 May 2024, using in situ data from the Swarm constellation. During the storm's main phase, enhancements in the EIA (equatorial ionization anomaly) were observed, forming strong super-fountains. The EIAs were extended toward latitudes beyond ±30° of the magnetic equator, with the crests of the EIAs being shifted to ∼25° of the magnetic equator on both hemispheres during the main phase of the storm. Swarm-A observed the strongest storm-time super-fountain during its entire age (2013-present) with nearly 500% increase in the crest density compared to the quiet-time conditions. During the recovery phase, the EIA was suppressed entirely, and density crests were observed over the magnetic equator, and troughs were observed at locations around ∼10° – 15°of magnetic dip latitude
Population dependent alteration in urban airborne bacterial communities enriched with pathogens: A study over Delhi, India
No full textUrban airborne bacteria demand more attention due to their diversity and ability to adapt in different ambient conditions, causing significant impact on human health. Current study investigates weather-dependent composition, diversity, and variability of urban airborne bacterial loading over Delhi, the most polluted metropolitan city in India. Simultaneous winter-time airborne bacterial samples are collected under different weather conditions, namely typical winter (TW), haze (HZ), rain (RN), and seasonal transition (ST) from winter to summer, over high and low populated region (HPR and LPR, respectively). Maximum bacterial diversity with highest cell count (13.1 ± 1.4 × 105 m-3) is noticed on HZ, followed by ST, TW, and RN. Winter haze could be responsible for proliferation of unique bacteria possibly due to abundance of nutrients in air. About 20 % increase in bacterial loading is recorded over HPR due to stronger emissions from human activities. 10 % bacterial genera are independent of spatial and temporal variation, representing urban background bacterial population. Beta diversities analysis revealed three distinct clusters, each corresponding to HZ, RN, and ST, due to significant variations in weather and air pollution. Ambient meteorology plays a major role in shaping bacterial diversity, contributing up to 60 %, while urban air pollution accounted for 20 %. Among meteorological parameters, temperature is most influential and positively correlated with bacterial diversity, while RH and wind speed are negatively correlated. Airborne pathogens like Acinetobacter and Corynebacterium, associated with respiratory diseases and skin infections, are in higher abundance in RN and warmer ST days. Present findings highlight public health risks posed by airborne pathogens over Delhi
Assessing the role of regional characteristics in estimating the volume of glacial lakes in the upper Indus-Ganga-Brahmaputra basins, Hindu Kush Himalaya
No full textGlacial lakes have exponentially increased in the recent decades across the world’s mountains, particularly in the Hindu Kush Himalaya (HKH), caused by rapid melting of glaciers. Consequently, their water volume and hence the hazard potential had also increased in recent decades. Robust water volumes of hazardous glacial lakes located in remote locations are rarely available, limiting the accuracy of current glacial lake outburst flood (GLOF) models that heavily rely on empirical water volume estimation equations. The majority of presently used equations are mainly based on data collected in the European Alps and have limited applicability in the HKH region. Thus, accurately predicting GLOF extents and likely damages in the downstream regions remains a critical challenge in the HKH region. In this study, we developed eight empirical equations to estimate mean depth (4) and volume (4) of glacial lakes in the upper Indus-Ganga-Brahmaputra (IGB) river basins. The study is based on a field-based bathymetric dataset of 25 glacial lakes from different parts of the upper IGB river basins. Separate equations were formulated for the major basins to understand the influence of regional lake characteristics on depth and volume estimations of glacial lakes. Our analysis revealed a non-linear negative relationship between the circularity ratio of glacial lakes and their mean depth, indicating that elongated lakes tend to be deeper than the circular ones. The average circularity ratio of glacial lakes in the upper IGB basins was 0.51 (as of 2020). We estimated the mean depth and total volume for a dataset comprising 19,284 glacial lakes in the upper IGB basins. The estimated mean depth and total estimated volume of these lakes in 2020 was 7.20 m and 28.88 km3, respectively. The empirical equations generated in the study based on the field-based bathymetry will be helpful in assessing the GLOF threats from continuously expanding glacial lakes in the upper IGB basins
Long range transport and local source(s) of moisture associated with precipitation in the western Himalaya (WH)
No full textWestern Disturbances (WDs) and the Indian Summer Monsoon (ISM) are the two principal weather systems driving the climate of the Hindu Kush Himalaya. WDs are dominant in the western Himalaya (WH) and ISM is dominant in the eastern Himalaya (EH). The Bay of Bengal (BoB) and the Arabian Sea (AS) are considered as the dominant sources of moisture for ISM. However, the source(s) of moisture associated with WDs is still debatable and unclear. We used precipitation isotopes and HYSPLIT modelling to understand the spatio-temporal patterns of precipitation isotopes and to estimate the contribution of various moisture sources to precipitation in the Upper Jhelum Basin (UJB), western Himalaya. The event based precipitation isotope data suggest that temperature and reversal of moisture source are the dominant climatological factors, and altitude as the dominant physiographic factor modifying the isotopic composition of precipitation in the region. Although there are many but discrete moisture sources associated with the precipitation brought by WDs and ISM including long range transport and local recycled moisture, the Arabian Sea provides a significant contribution for both systems. Monthly negative vertical wind velocity and less Outgoing Long Radiation (>240 W/m2) indicated significant convection processes throughout the year. HYSPLIT modelling and Isotope-enabled Bayesian results suggested that the long range transportation of advected moisture is dominant (53 ± 11 %) and increases with increase in altitude. The contribution from transpiration is 29 % (±7). It was also observed that out of local moisture, transpiration contributes significantly to lower altitude precipitation stations (<2000 m, asl) in summer. The study highlighted the significance of various moisture sources in shaping the hydrological regimes of the western Himalaya and highlights the role of environmental tracers to assess the hydrodynamics of the region