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Risk assessment and conservation strategies of Gujarat Chalcolithic sites using remote sensing and Geographic Information System (GIS)
No full textTunable Titanium and Tantalum oxide coatings as highly efficient antibacterial agents
No full textThis study evaluates the bactericidal efficacy of non-stoichiometric titanium oxide (TiOx) and tantalum oxide (TaxOy) thin films, synthesized through radio frequency (RF) magnetron sputtering under varying process conditions. Structural and chemical analyses reveal that TiOx films undergo a transformation from an amorphous to an anatase crystalline structure when oxygen is incorporated and/or when subsequently heat-treated at 823 K. In contrast, TaxOy films retain their amorphous structure regardless of the oxygen content during deposition. However, annealing TaxOy films at 1073 K leads to the formation of β-TaxOy phases. Despite variations in film thickness, both oxide films exhibit high optical transmittance (∼80 %), making them suitable for aesthetic coatings. These films are tested for bactericidal activity against two bacterial strains, Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive), to assess their effectiveness against different bacterial cell wall types. Here, among these fabricated TiOx and TaxOy films, the amorphous, non-stoichiometric TaxOy films (with a cation-to-anion ratio of 1:2.3) outperform previous reports, achieving a 17.0 % survival rate against E. coli. However, both oxide films demonstrate significant bacterial survival against S. aureus (as low as ∼ 35 % for TiOx thin film). The comparable wettability and surface roughness across all films further indicate that intrinsic material properties, such as ion release, are likely responsible for the observed enhancement in bactericidal efficacy
Styryl benzoxazolium salts as environment-sensitive mitochondrial probes for imaging ferroptosis
No full textStyryl benzoxazolium salts are promising fluorescent scaffolds, yet systematic studies on their structure-property relationships and biological applications remain limited. To address this gap, we synthesized five novel derivatives (A1-A5) bearing diverse electron-donating groups and evaluated their photophysical behavior, viscosity sensitivity, and bioimaging performance. All derivatives exhibited strong intramolecular charge transfer (ICT) character, high environmental sensitivity, and notable Stokes shifts, with A5 showing near-infrared emission and significant viscosity-dependent fluorescence enhancement (53-fold). Probes A1, A2, A4, and A5 selectively targeted mitochondria in live COS-7 cells with high Pearson correlation coefficients (PCC > 0.82), while A5 additionally enabled real-time monitoring of mitophagy and mitochondrial viscosity changes during ferroptosis. Cytotoxicity assays confirmed their biocompatibility up to 40 μM, and A5's responsiveness was validated via ferrostatin-1 rescue and malondialdehyde assays. These findings establish A1-A5 as structurally tunable, organelle-specific fluorophores with diagnostic potential for cellular dynamics and regulated cell death pathways. Our study is the first to explore the imaging performance and biological applications of this dye class, establishing a foundation for the rational design of advanced probes in cell biology
Geomorphic diversity of dryland rivers and their controls in the semi-arid region, Western India
No full textDrylands cover approximately 41% of the global land area and support diverse fluvial systems. Identifying the geomorphic diversity of dryland rivers and their maintenance is essential for sustaining ecosystems in arid and semi-arid regions. Furthermore, amidst climate change and the anticipated expansion of dryland areas, gaining insights into this diversity is crucial for developing adaptive and effective management strategies for dryland rivers. However, dryland rivers are often generalized, with studies focusing more on their distinct characteristics than the inherent geomorphic diversity that shapes river character and behaviour. A comprehensive understanding of the occurrence, spatial distribution, and major controls on channel morphological diversity of dryland rivers is still lacking. To address this gap, we have examined the geomorphic diversity within and across two semi-arid dryland river basins in western India: the Mahi River Basin (MRB) and the West Banas River Basin (WBRB). We employed River Styles classification for geomorphic characterization, combined with hydrological analysis, total stream power and specific stream power assessment for a more comprehensive evaluation. Hydrological analysis indicates that MRB and WBRB are monsoon-dominated rivers. MRB is a perennial dryland river with high flow permanence downstream, whereas WBRB is intermittent, with discharge decreasing downstream. Geomorphic characterization shows that MRB predominantly exhibits a confined, terrace margin controlled, meandering, gravel bed River Style. Only a small section of the estuarine zone exhibits a partly confined, terrace margin controlled, fine-grained bed River Style. Terraces impose antecedent confinement on the contemporary river processes in the MRB, limiting floodplain development. On the contrary, WBRB predominantly features laterally unconfined, continuous channel, low sinuosity, gravel-to-sand bed River Style with extensive floodplain development. The midstream section shows a partly confined, terrace margin controlled, gravel bed River Style in the pediment zone. Stream power analysis showed high stream power even in the mid-to-downstream pediment zone of both basins, primarily driven by site-specific structural controls influencing current channel processes. Field investigations indicated that erosion processes, notably plucking, predominantly shape the reaches with higher stream power. The maximum specific stream power in the pediment zone is 98 W/m² and 255 W/m² in the WBRB and MRB, respectively. Geomorphic diversity within the basin is primarily shaped by geological control in the rocky uplands, while the pediment and alluvial zones reflect a combination of geological controls and Holocene climatic imprints. Although both basins are in semi-arid regions, the observed geomorphic diversity across the basin is governed by stream power distribution patterns with underlying geological controls and valley evolution at the millennial time scale. Insights from this study can enhance ground-level river management practices by incorporating the diversity of dryland rivers and contributing to the global inventory, thereby enriching our understanding of dryland river systems
Multi-day extreme precipitation caused major floods in India during summer monsoon of 2024
No full textClimate change has increased the risk of extreme precipitation and flooding in India. During the 2024 summer monsoon season, three major extreme precipitation events occurred across the western, southern, and northern states of India, leading to widespread flooding in these regions. We examine the causes and impacts of extreme precipitation and flood events using a combination of observational data, reanalysis datasets, and hydrological models. In all the three regions, extreme rainfall occurred immediately after multiday continuous precipitation, resulting in catastrophic flooding. The 3-day extreme precipitation that caused flooding in the three regions had return periods of more than 75 years, 100 years, and 200 years, respectively. The primary moisture source for the Gujarat floods (western India) was the Arabian Sea, while the floods in Andhra Pradesh and Telangana (southern India) were driven by dual moisture advection from both the Arabian Sea and the Bay of Bengal. For the floods in northern India, the dominant moisture sources were recycled land moisture and southwest moisture transport from the Arabian Sea. These moisture inflows, combined with favorable atmospheric conditions and pre-existing saturated soils, resulted in severe flooding across all regions. Our findings underscore the escalating challenge of managing such extreme events as their frequency and intensity rise with global warming
A Single-Phase Grid-Tied Transformer-Less Multilevel Solar Inverter With Voltage Boost
No full textThis work proposes a single-phase multilevel grid-tied transformer-less solar inverter with voltage boost. The system comprises of two cascaded stages: the first is a partially rated dc-dc boost converter to create four dc voltage levels, while the second is a new topology of single-phase multilevel sinusoidal pulse width modulated (SPWM) inverter at rated volt-ampere (VA) coupled to the dc-dc converter output voltage levels. This scheme does not require capacitor voltage balancing due to the floating dc supply created in the dc-dc conversion stage. The inverter is controlled using a multicarrier SPWM logic. This scheme exhibits near sinusoidal line current, hence offering reduced filter requirements and reduced common mode currents during grid integration. The device losses in this scheme are low compared to the existing schemes, thus reducing heat-sink requirements. The voltage boost capability becomes cost-effective due to the partial rated conversion stage that offers seamless integration of the inverter at the grid voltage without any additional coupling transformer. Simulation and experimental study confirm the effectiveness of the proposed scheme in applications of single-phase grid interfaced harnessing of solar photovoltaic energy and injecting the power to the utility network
Machine learning based gap filling of streamflow and water level observations in India, 1961-2021
No full textContinuous hydrological observations are essential for accurate modelling and informed water resource management. However, significant data gaps in streamflow and water level observations, compounded by extreme hydroclimatic events and quality control issues, impede robust hydrological analyses. We employed geomorphological, meteorological, and hydrological parameters in combination with machine learning to fill gaps in streamflow and water level observations at 343 stations across Peninsular India. We categorized stations into similar-behaving classes using K-means clustering on catchment characteristics to improve model performance and fill the data at ungauged locations. The machine learning approach showed Nash Sutcliffe Efficiency (NSE) of more than 0.90 for water level and streamflow at 78% and 91% of stations, respectively. The machine learning model�s performance decreases with increasing the duration of missing data. However, the average NSE remained above 0.85. The gap-filled streamflow record for the 1961-2021 period highlights a spatial decoupling between rainfall and streamflow trends, indicating the considerable influence of anthropogenic activities in India. Overall, the gap-filled streamflow and water level observations for 1961-2021 are valuable for the planning of hydrological assessment and water resources
Light-Assisted Oxidative Functionalization of Indoles by Re-(I)Dipyrrinato Catalyst
No full textThis work is focused on the photocatalytic chemodivergent oxidation of indoles by Re(I)dipyrrinato complex. Due to strong absorption in the visible region and high singlet oxygen quantum yields, the Re(I)dipyrrinato complexes can act as highly efficient photocatalysts. A chemodivergent photooxidation of indoles was demonstrated under an oxygen atmosphere featuring low catalyst loading (0.25 mol%) and short reaction time with blue LEDs. A variety of substrates viz., 3-methyl indoles, 2,3-dimethylindoles, N-protected indoles, and 2-methylindoles were utilized to produce N-(2-acetylphenyl)formamide, N-(2-acetylphenyl)acetamide, N-(2-formylphenyl)acetamide, and 2,2-disubstituted indoline-3-ones, respectively, in good to high yields. Mechanistic investigations revealed that the Re(I)dipyrrinato complex in the excited state is involved via photoinduced electron transfer (PET) and energy transfer (EnT) in these reactions. The method is notable for its mild conditions, operational simplicity, and wide scope, suggesting the potential application of Re(I)dipyrrinato complex as an advantageous photocatalyst
Experimental and theoretical study of size-dependent phase evolution in NaCl-KCl alloys
No full textIn the present investigation, the formation of nanocrystalline bi-alkali halide (NaCl+KCl) obtained by combined low temperature (cryomilling) with room temperature (RT) milling was reported. The cryomilling, which is endowed with special ability to accelerated fracture and form free ionic salt crystals, is utilized for rapid refinement. This is followed by RT milling to form biphasic nanocrystallites. The bi-phase formation with the time of milling was characterized using a scanning electron microscope (SEM) and transmission electron microscope (TEM). The change in lattice parameter and introduction of micro-strain in the lattice (due to cold work and bi-phase formation) have been characterized using X-ray diffraction and deduce using theoretical calculations. The investigation reveals the influence of milling time on the shape and size of the crystallites along with formation of biphasic NaCl-KCl crystallites with inner core being NaCl surrounded by KCl crystals. The KCl powder particles get deposited on the surface of NaCl crystals to maintain the charge neutrality during ball milling. The shape of NaCl undergoes change from cuboid to cuboctahedron with the progression of milling time due to plastic deformation induced roughing. The temperature-dependent mechanical behaviour and associated mechanism of the milled NaCl-KCl system were discussed and supported by the thermodynamic modal. It is evident, NaCl-KCl is phase separating system, which accentuated at nanosized and hence, the formation of biphasic crystalline structure is observed during combined cryo and RT milling
