130553 research outputs found
Sort by
Effect of particle concentration at outer coffee stain edge on the limit of analyte detection via surface-enhanced Raman spectroscopy
No full textDeveloping highly sensitive and selective sensors for molecule detection is a critical objective in advancing various technological fields. Numerous methodologies have been employed to create nanomaterial-based sensors that detect molecules at very low concentrations. Among these, colloidal droplet evaporation stands out as a straightforward and efficient technique for developing distinct nanomaterial deposition morphologies, thereby enhancing the sensitivity and selectivity of the sensor. In this study, tunable, multilayer, smectic assemblies of gold nanorods (Au-NRs) constituting coffee stain patterns on a hydrophilic silicon substrate are demonstrated to facilitate reproducible and ultra-low detection of analyte molecules through surface-enhanced Raman spectroscopy (SERS). Smectic arrangements of Au-NRs with side-to-side and end-to-end orientations occur at the outer coffee stain edge after the evaporation of a sessile Au-NR dispersion droplet. The thickness and height of the outer coffee stain edge—and consequently the self-assembled structures of Au-NRs—can be finely controlled by varying the particle concentrations in the evaporating colloidal droplet. We utilized the smectic structures of Au-NRs as a template for detecting very minute amounts of an analyte molecule, Rhodamine B (RhB), known to be toxic to humans and the environment. We demonstrate here that when the metallic nanorod concentration increased by only two decades, the limit of detection of the analyte molecules improved by six orders of magnitude. This work demonstrates the direct correlation between the minimum detection limit of the analyte molecule using SERS and the extent of the self-assembled anisotropic nanoparticle structures, quantified using microscopic techniques, formed at the outer coffee stain edge
Assessment of fiber orientation and order in carbon fiber reinforced polymer composites using induction thermography and Radon transform analysis
No full textThe mechanical properties of carbon fiber reinforced polymer (CFRP) composites are critically influenced by th e fiber orientation and stacking sequence of individual layers. Any misalignment in the global ply orientation can lead to significant performance degradation and potential operational failure. This paper introduces an advanced method for identifying fiber orientation and its order in CFRP structures using Radon transform analysis of infrared thermal patterns generated through induction heating with a circular coil in transmission mode. The fiber orientation within the composite layers directs the flow of induced current, thereby affecting the resulting heating patterns. Radon transform allows to extract the hidden spatial characteristics of the heating patterns and thus the fiber orientations. The proposed method has been demonstrated on CFRP samples up to six layers. The results indicate a precision of the order of 7°, indicating the Radon transform method’s high accuracy in estimating fiber orientation in CFRP composite structures. This approach not only provides a reliable means to assess the internal fiber orientation, but also effectively identifies the sequence in which the orientation appear, contributing to a comprehensive understanding of the laminate structure. The ability to detect fabrication inconsistencies, such as fiber waviness, further highlights the robustness of this technique
Metagenomic profiling of cyanide-degrading microbial communities in steel industry wastewater with an implication for bioremediation
No full textExtremely toxic cyanide-contaminated wastewater discharged from steel industries poses serious environmental and health risks. Cyanide removal through physical and chemical treatments has cost-intensive operational challenges. Microbial bioremediation is cost-effective and environment friendly. As microorganisms can degrade cyanide by utilizing it as a source of nitrogen and converting it into less toxic compounds such as ammonia, this study was planned to get metagenomic data first and then potential microbial strains from the contaminated samples. In this study, wastewater samples from the equalizer and the sludge thickener tank of a steel wastewater treatment plant showed high cyanide concentration (mg/L) of 21.6 and 27.59, respectively. The free form of cyanide was predominant as the wastewater pH was ⩾ 9. The contents of anions (F-, Cl-, NO2-, Br-, NO3-, SO42-) and elements (Na, Al, K, Fe) were also on the higher side. The metagenomic study revealed microbial community structure and taxonomic abundance with dominance of cyanide-degrading bacterial genera in the wastewaters, viz., Bordetella, Achromobacter, Pseudomonas, and Burkholderia, providing an opportunity to screen and obtain the efficient CN-degrading strains. Bacteria belonging to the phylum Deinococcus and the genus Mesorhizobium were reported for the first time from cyanide-contaminated water. Also, functional analysis showed high prevalence of genes encoding enzymes critical to cyanide degradation pathways e.g., rhodanese, nitrilase, nitrile hydratase, amidase, cyanide-insensitive terminal oxidase, and malate:quinone oxidoreductase. Eight distinct alkaliphilic cyanotropic microorganisms were successfully isolated and shown to degrade cyanide effectively at pH 9.5, indicating their metabolic adaptation to cyanide toxicity and alkaline stress. These findings can lead to a microbial technology against cyanide contamination
Compound weather and climate extremes in the Asian region: science-informed recommendations for policy
No full textAnthropogenic climate change has led to rapid and widespread changes in the atmosphere, land, ocean, cryosphere, and biosphere, leading to more pronounced weather and climate extremes globally. Recent IPCC reports have highlighted that the probability of compound extreme events, which can amplify risk, has risen in multiple regions. However, significant gaps remain in our understanding of the drivers and mechanisms behind these events. This concept paper discusses compound events in the Asian region in the context of its unique and diverse geographical settings, and regional climatic features including the seasonal monsoons. Notably, Asia is the world's most disaster-affected region due to weather, climate, and water-related hazards. Therefore, an integrated understanding of how climate change will impact compound events in this region is essential for effective forewarning and risk mitigation. This paper analyzes three typologies of compound events in the Asian region, illustrating their regional complexity and potential linkages to climate change. The first typology pertains to compound floods, for example, the devastating floods in the Indus River Basin and adjoining Western Himalayas during 2022 caused by the combined effects of heavy monsoon rainfall, intense pre-monsoon heatwaves, glacier melt, and modes of climate variability. The second typology relates to compound heatwave-drought events that have prominently manifested in East and South Asia, and are linked to large-scale drivers of the land-atmosphere–ocean coupled system and local feedbacks. The third typology relates to marine extremes involving the compounding effects of ocean warming, sea-level rise, marine heatwaves, and intensifying tropical cyclones. We identify key knowledge gaps in understanding and predicting compound events over the Asian region and discuss advances required in science and technology to address these gaps. We also provide recommendations for the effective utilization of climate information towards improving early warning systems and disaster risk reduction
A low molecular weight iron metallogel as an OER catalyst
No full textMetallogels (MOGs), a fascinating class of soft materials, have received significant attention recently due to their unique properties and versatile applications. An intriguing method has been utilized for the synthesis of a stimuli-responsive Fe-MOG having a flower-like morphology, utilizing 2-amino terephthalic acid as the gelator in N, N −dimethylformamide solvent. The morphology of the gel was determined by various microscopic techniques, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The mechanical properties of the as-synthesized Fe-MOG metallogels were assessed through rheological studies. Several analytical methods, including fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and MALDI-TOF, provided insights into the chemical composition, bonding configurations, and structural characterization of the Fe-MOG. The Fe-MOG addresses the ongoing challenge of developing a durable and economically viable electrocatalyst for the oxygen evolution reaction (OER). The OER activity of the dry form of the gel under alkaline conditions has been carefully evaluated. The dry gel requires an overpotential of only 380 mV to deliver 100 mA cm–2. Moreover, the Fe-MOG catalysts maintained consistent performance throughout a stability test spanning 2000 cycles. This novel approach provides a cost-effective solution for designing OER electrocatalysts with high catalytic activity and outstanding stability
The representation of temperature over Northeast India: assessing the performance of CORDEX‑CORE model experiments
No full textPerformance of the latest high-resolution COordinated Regional Climate Downscaling EXperiment-Coordinated Output for Regional Evaluation (CORDEX-CORE) model experiment suites for simulating temperature over Northeast India (NEI) during 1979-2005 are assessed. Three different suites of Regional Climate Models (RCMs), i.e., COSMO, RegCM4.7 and REMO suites dynamically downscaled from three different Global Circulation Models (GCMs) available over the CORDEX South Asia domain are considered. The three RCMs are evaluated to assess the performance in simulating the spatial pattern of temperature over the study area. The model experiments could simulate pre- and post-monsoon temperatures fairly well as compared to monsoon and winter seasons. The RCMs show a higher positive correlation coefficient (CC) of 0.9 – 0.98. Over the majority of NEI, the added value (AV) and Brier skill score (BSS) exhibit positive values of 0.4-0.8 and 0.2-0.8 respectively, indicating additional information and/or improvement after downscaling. The inter-comparisons show that the present-day temperature over the study region is better captured in the ensemble than in the individual model. Individually, the MPI_LR_COSMO model better simulates the spatial pattern of temperature with a higher spatial correlation of ~ 0.956 than the other RCMs. The temperature extremes are also well represented spatially by the model. Overall, the COSMO model experiment suites were identified to be the best with the corresponding observation across the year over NEI
Late Holocene Climatic Record in the Northeastern Part of the Deccan Trap Region, Maharashtra, India: Episodic Intensification and Weakening of the Monsoon
No full textA high-resolution paleoclimatic reconstruction from the Tirna River basin in the Deccan Volcanic Province (DVP) of western India, covering about 2022 - 1596 calibrated years BP, is presented in this paper. The study combines magnetic susceptibility (χ) and elemental geochemistry ratios (Fe/Al, Ti/Al, K/Na, K/Al, Ca/Al, Mn/Al, and Mg/Al) to infer weathering regimes, detrital input patterns, and sedimentary processes controlled by climate. An initial wet and erosive period (~1596–1707 cal yr. BP) characterised by high Fe/Al, Ti/Al, and χ values, reflects intense monsoon-driven detrital input, and represents one of the several climatic sequences captured in the record. A transitional period with decreasing magnetic susceptibility and Fe/Al ratios (~1722–1785 cal yr. BP) follows, indicating reduced runoff and possible monsoon variability. When chemical weathering markers peak between 1840 and 1872 cal yr. BP, it suggests a humid period with more intensified pedogenesis. Declining χ and subsequent increases in Ca/Al and Mg/Al (~1903–1974 cal yr. BP) indicate reduced erosion and a shift towards warmer and more stable conditions. A shift to cooler, drier, and more stable environmental conditions is indicated by the rapid fall in weathering proxies and χ during the most recent phase (~1993–2022 cal yr. BP). These climate changes are consistent with known regional and global paleoclimatic events, including the beginning of the Dark Ages Cold Period, the end of the Roman Warm Period, and the well-documented monsoon weakening event around 2.0 ka BP. The results demonstrate sensitivity of the DVP landscape to variations in the Indian Summer Monsoon. Overall, this study highlights the value of multi-proxy sediment records for reconstructing past monsoon variability and enhances our understanding of Late Holocene hydroclimatic dynamics in peninsular India
Higher order discontinuous Galerkin finite element methods for the contact problems
No full textIn this chapter, we study the a posteriori error analysis of higher order discontinuous Galerkin finite element methods for two contact problems, namely, the obstacle problem and the Signorini problem. The reliability and efficiency of proposed a posteriori error estimators are discussed. An appropriate construction of discrete Lagrange multipliers and residual functional plays a crucial role in establishing the reliability estimates. The analysis is carried out in a unified setting which holds for a class of discontinuous Galerkin finite element methods. Numerical results are presented to demonstrate the convergence behavior of the error estimator
Underestimation of Historical Terrestrial Water Storage Droughts in Global Water Models
No full textEnhanced drought modeling is crucial for realistic prediction and effective management of water resources, especially with climate change anticipated to exacerbate drought frequency and severity. Global water models (GWMs) simulate historical and future terrestrial water storage (TWS) with continuous spatial and temporal coverage. However, a global evaluation of TWS simulations by GWMs focused on drought is lacking. Here we evaluate, for the first time, GWMs' capability to represent TWS droughts by comparing simulations with Gravity Recovery and Climate Experiment satellite data. We find notable underestimation of drought severity and coverage by GWMs, across diverse regions, including North America, South America, Africa, and Northern Asia. When examined without trend removal, the underestimation of TWS droughts is more pronounced in recent years (2016–2019) compared to 2002–2015, especially in northern latitudes. This underrepresentation highlights the necessity to improve GWMs to simulate TWS droughts. Our results imply that previously reported future TWS projections could have underestimated droughts
Secretome of hypoxia-preconditioned apoptotic wharton's jelly mesenchymal stem cells: A superior non-cellular approach for managing acute graft-versus-host disease
No full textBackground:
The therapeutic potential of MSCs in treating aGVHD is often questioned due to their undetectable presence post-administration, highlighting importance of their secretome. Our study explores immunomodulatory effects of WJ-MSCs (viable/hypoxia preconditioned apoptotic) and their culture-conditioned media (CCM) in aGVHD.
Methods:
Human MSCs were isolated from Wharton's Jelly (WJ) and preconditioned under hypoxia (1% O2) with 1μM staurosporine (STS) for 24 hours to generate WJ-MSCsHYP+APO. CCM were collected after 48 hours from WJ-MSCs and WJ-MSCsHYP+APO. Their immunomodulatory effects were evaluated in vitro by assessing T-cell proliferation, Tregs induction, macrophage polarization, Th1/2/17 subtypes, mitochondrial ROS, and membrane potential. A comparative analysis of CCM from WJ-MSCs, WJ-MSCsHYP+APO, and their co-culture with aGvHD patients-derived aPBMNCs was performed using LC-MS/MS, alongside in vivo testing in a chemotherapy-based aGVHD murine model.
Results and Conclusion:
WJ-MSCs were more effective than WJ-MSCsHYP+APO in inhibiting T-cell proliferation (77.23% vs 93.71%; p ≤0.0001). In contrast, WJ-MSCsHYP+APO outperformed in enhancing Tregs (10.08% vs 16.99%; p ≤0.01) and promoting M2 macrophage polarization (19.26% vs 72.89%; p ≤0.0001). WJ-MSCsHYP+APO-CCM was superior to WJ-MSCs-CCM in suppressing T-cell proliferation (21.03% vs 51.25%; p ≤0.001), increasing Tregs (24.73% vs 11.67%; p ≤0.0001), and promoting M2 macrophages (92.48% vs 42.85%; p ≤0.0001) while reducing mitochondrial ROS (12.638% vs 62.638%; p: ≤0.0001) and polarizing mitochondria (9.172 vs 0.872; p: ≤0.0001) effectively. It also significantly decreased the Th1/Th2 ratio (1.21 vs 12.84; p ≤0.0001).
Bioinformatic analysis revealed 336 and 369 differentially expressed proteins in secretome of WJ-MSCs and WJ-MSCsHYP+APO, respectively, when co-cultured with aPBMNCs from aGvHD patients. WJ-MSCsHYP+APO-CCM enriched in proteins that regulate immune responses and maintain homeostasis through complement (100.0%), and carbohydrate metabolism (50.0%) while promoting M2 macrophage polarization, Tregs generation, and reducing oxidative stress, evidenced by downregulation of proteins involved in aerobic glycolysis (66.67%), gluconeogenesis (66.67%), antigen processing and activation (16.67%). It also protects against secondary infections by upregulating antimicrobial peptides (50.0%) and fine-tuned inflammation by modulating coagulation (73.08%). Both MSCs and their CCM demonstrated efficacy in alleviating GVHD in vivo model, as evidenced by increased weight, reduction in skin ruffling, hunching, eyelid closure, and diarrhea. Notably, the WJ-MSCsHYP+APO-CCM produced a more pronounced therapeutic effect than MSCs and might be used as a non-cellular therapeutic approach for managing aGVHD