The application of a tube combustion system (pyrolyzer) for the batch combustion of low carbon content environmental matrices, such as soil and sediment, for determining 14C specific activity is examined. The samples were combusted at 600°C, and the CO2 species produced were trapped in 3N NaOH, precipitated as BaCO3 by adding BaCl2, and subjected to acid-hydrolysis to transfer the CO2 species to the absorber-scintillator mixture for liquid scintillation counting (LSC). The method was validated by analyzing the samples by accelerator mass spectrometry (AMS) method. The minimum detectable activity (MDA) for the method, at 2σ confidence level, was 10 Bq kg–1C (4 pMC) for a counting time of 500 min and 7 Bq kg–1C (3 pMC) for 1000 min. The capability of the method to quantify a small excess of 14C specific activity (a few Bq kg–1C or pMC) in the environment of a nuclear facility, when compared to the ambient natural background level, was demonstrated by analyzing a total of 23 soil and 7 sediment samples from the vicinity of a pressurized heavy water reactor (PHWR) nuclear power plant (NPP) at Kaiga, India. The maximum excess 14C specific activity values recorded for soil and sediment matrices were 37 ± 7 Bq kg–1C and 11 ± 7 Bq kg–1C, respectively, confirming minimal radioecological impact of the operation of the NPP on the environment. The 14C specific activity ratio for the recently fallen leaf litter and the soil underneath at most of the sampling points in the vicinity of the NPP had a mean value of 1.03 with an associated standard deviation of 0.07. Statistical tests confirm that the mean values of the data set of 14C specific activity of leaf litter and underlying soil are not significantly different.

Most clay minerals are characterized by a platy morphology. By contrast, palygorskite has a fibrous morphology and is structurally distinct from the typical 1:1 and 2:1 layer structures. Diverse opinions exist on the origin of palygorskite in soils. Many authors suggest that palygorskite forms after smectite. Others favor its authigenesis during pedogenic processes or its inheritance from the parent material. This review provides a critical synthesis on the origin of palygorskite in the semi-arid-tropical (SAT) Vertisols and arid calcic soils of the Thar Desert of India. It also highlights the specific genetic pathway for the presence of palygorskite in the soils. The ubiquitous association of smectite with palygorskite is inadequate to explain the formation at the expense of smectite, because at pH 8.2 and above the smectite structure is subjected to dissolution to create soluble Si and Al, and the recrystallization of the soluble Si and Al to form palygorskite may not be possible in the Vertisols of the Indian SAT environment. Thus, mildly to moderate alkaline pedochemcial environments of the SAT Vertisols do not favor authigenic precipitation of the palygorskite in such soils. This review shows that the presence of palygorskite in the SAT Vertisols is due to its inheritance from the exhumed inter-trappean beds, infra-trappean beds, and bole beds. This view on the genesis of the palygorskite is also justified by its presence in weakly developed calcic soils of the Thar Desert as detrital flux from the adjoining marine sedimentary rocks.

Micromorphological studies were performed in order to understand the factors and processes involved in the formation of calcium carbonate (CaCO3) in twenty three soil series of Vertisols representing sub-humid, semi-arid and arid climatic regions of Peninsular India. The study indicates that Vertisols contain both pedogenic calcium carbonate (PC) and non-pedogenic calcium carbonate (NPC) irrespective of the ecosystems to which they belong. The NPCs are part of the parent material of Vertisols. Dissolution of NPCs and recrystallization of dissolved Ca2+ ions are responsible for the formation of PCs. Vertisols of arid and semi-arid climates contain more PC in their soil control section (SCS) than those of sub-humid climates. Formation of PC is the prime chemical reaction responsible for the increase in pH, the decrease in the Ca/Mg ratio of exchange site with depth and in the development of subsoil sodicity. Petrographic and scanning electron microscopic (SEM) examination of quartz, feldspars and micas indicate little or no alteration, discounting the possibile formation of smectite during Vertisol formation. X-ray diffraction (XRD) analysis of clays indicates that smectites of Vertisols are fairly well crystallized and do not show any sign of transformation except for hydroxy interlayering. The preservation of the crystallinity of smectite and the lack of transformation of primary minerals thus validate the hypothesis of positive entropy change during the formation of Vertisols.

The precise cause-effect relationship between CaCO3 of pedogenic and non-pedogenic origin, and exchangeable Mg, Na and Ca percentages (EMP, ESP and ECP) has been established in the study. This indicates that impoverishment of Ca2+ ions on the exchange sites of Vertisols needs to be controlled by rehabilitation methods that can replenish Ca2+ ions, and thus the study provides relevant information for future land resource management programmes not only on Vertisols of India but also on similar soils occurring elsewhere.

A total of 32 sweet potato genotypes were evaluated to assess the genetic diversity based on quantitative traits and molecular markers, as well as stability for yield and related traits. Wider variability was observed for the traits like vine length (181.2–501.3 cm), number of leaves/plant (103.0–414.0 cm), internodal length (3.20–14.80 cm), petiole length (6.5–21.3 cm), leaf length (8.50–14.5 cm), leaf breadth (8.20–15.30 cm), leaf area (42.50–115.62 cm2), tuber length (7.77–18.07 cm), tuber diameter (2.67–6.90 cm), tuber weight (65.60–192.09 g), tuber yield (7.77–28.87 t ha−1), dry matter (27.34–36.41%), total sugar (4.50–5.70%) and starch (18.50–29.92%) content. Desirable traits such as tuber yield, dry matter and starch content have shown high heritability (>60%) with moderate to high genetic advance. Under molecular analysis, a total of 232 alleles were observed from all 32 microsatellite markers, which ranged from 4 to 14 with an average of 7.77 alleles per locus. In the population, the average observed heterozygosity (0.51) was higher than the expected heterozygosity (0.49). The contribution of genotype, genotype by environment interaction to the total variations was found to be significant. Based on the multi-trait stability index (tuber length, tuber diameter, tuber weight and tuber yield), genotypes X-24, MLSPC-3, MLSPC-5, ARSPC-1 and TSP-12-12 were found to be most stable. Among them, the high-yielding and stable genotypes TSP-12-10 (26.0 t ha−1) and MLSPC-3 (23.9 t ha−1) can be promoted for commercial production or used as parental material in future crop improvement programmes.

The Palaeocene–Eocene Thermal Maximum (PETM) was a global extreme climatic event, but it is relatively unknown from lower latitudes or equatorial regions in comparison to mid- and high latitudes. The present study provides the first clay mineralogical evidence of the PETM and subsequent hyperthermal events in a near-equatorial region represented by the Akli Formation in the Barmer Basin, India. The 32 m-thick succession of the Akli Formation shows abrupt changes in smectite and kaolin abundances preceding, during and succeeding the PETM event. Within the studied section, the kaolin content increases from 5–8% pre-PETM to 30–35% during the PETM, and then again decreases to 5–6% during the post-PETM period. The smectite, however, is marked by a corresponding decrease and its transformation into kaolin in acid weathering conditions. The transformation of the smectite is first marked by hydroxy interlayering and then transformation into kaolin during the PETM. The transformation of smectite into kaolin also resulted in extensive precipitation of iron oxide in sediments. The clay mineralogical changes in the Palaeocene–Eocene transition sediments of the Akli Formation were caused by 3–5°C warming and a 25–50% increase in rainfall during the hyperthermal events. Unusually high charcoal (~20%) fragments during the Palaeocene–Eocene transition also suggest warming and widespread biomass burning during the PETM in the lower latitudes.

The quantification of fossil-fuel derived carbon dioxide (CO2ff) emissions is critical for regional carbon budgets. Radiocarbon (14C) is an effective tool to estimate the contribution of CO2ff to the total atmospheric CO2. In the present study, we have determined the spatial distribution of fossil fuel derived CO2 across Delhi using 14C measurements in Peepal tree leaves from April 2016 to March 2017 at city scale. Our analysis results show that the Δ14C values vary between –67.78‰ to 5.61‰ and corresponding CO2ff values are varying from 1.63 ppm to 33.34 ppm. CO2ff values from campus sites vary between 6.99 ppm to 16.38 ppm with an average value of 10.22 ± 3.20 ppm, while CO2ff values vary from 2.41 ppm to 33.34 ppm with an average value of 13.32 ± 9.40 ppm for sites located in the parks. Further, we observed the higher contributions of fossil fuels in the CO2 from northwest Delhi, central Delhi, and some parts of east and southwest Delhi. In the absence of real-time CO2 monitoring, the results of this study provide a potential method for analyzing the contribution of CO2ff values over the urban landscape to total CO2 over the study region.

This study describes the morphological and dynamic changes of Parkachik Glacier, Suru River valley, Ladakh Himalaya, India. We used medium-resolution satellite images; CORONA KH-4, Landsat and Sentinel-2A from 1971–2021, and field surveys between 2015 and 2021. In addition, we used the laminar flow-based Himalayan Glacier Thickness Mapper and provide results for recent margin fluctuations, surface ice velocity, ice thickness, and identified glacier-bed overdeepenings. The results revealed that overall the glacier retreated by −210.5 ± 80 m with an average rate of 4 ± 1 m a−1 between 1971 and 2021. Whereas a field study suggested that the glacier retreat increased to −123 ± 72 m at an average rate of −20 ± 12 m a−1 between 2015 and 2021. Surface ice velocity was estimated using COSI-Corr on the Landsat data. Surface ice velocity in the lower ablation zone was 45 ± 2 m a−1 in 1999–2000 and 32 ± 1 m a−1 in 2020–2021, thus reduced by 28%. Further, the maximum thickness of the glacier is estimated to be ~441 m in the accumulation zone, while for glacier tongue it is ~44 m. The simulation results suggest that if the glacier continues to retreat at a similar rate, three lakes of different dimensions may form in subglacial overdeepenings.

A compact, two-element textile MIMO antenna is designed with enhanced isolation by using modification in the ground, open-ended slots along with shorting pins. Maximum 27.8 dB isolation is achieved in two-element antennae, where the edge-to-edge distance is kept at 0.19 λ0 which is less than the conventional half wavelength. The Y-shaped decoupling and shorting pins improve the isolation up to 14 dB and can mitigate the current moment between the two ports effectively. The open slots in the ground are enhancing the mutual impedance and shift the operating band of the antenna toward the lower frequency band and thus size miniaturization is also achieved. The textile antenna achieves a 10 dB impedance bandwidth from 4.24 to 5.38 GHz with more than 21.1 dB isolation in the entire band. The phantom wrist model and bending analysis are carried out with the textile antenna to validate the on-body effects of the antenna in wearable and 5G applications.

The oceans store a substantial fraction of carbon as calcium carbonate (CaCO3) and organic carbon (Corg) and constitute a significant component of the global carbon cycle. The Corg and CaCO3 flux depends on productivity and is strongly modulated by the Asian monsoon in the tropics. Anthropogenic activities are likely to influence the monsoon and thus it is imperative to understand its implications on carbon burial in the oceans. We have reconstructed multi-decadal CaCO3 and Corg burial changes and associated processes during the last 4.9 ky, including the Meghalayan Age, from the Gulf of Mannar. The influence of monsoon on carbon burial is reconstructed from the absolute abundance of planktic foraminifera and relative abundance of Globigerina bulloides. Both Corg and CaCO3 increased throughout the Meghalayan Age, except between 3.0–3.5 ka and the last millennium. The increase in Corg burial during the Meghalayan Age was observed throughout the eastern Arabian Sea. The concomitant decrease in the Corg to nitrogen ratio suggests increased contribution of marine organic matter. Although the upwelling was intense until 1.5 ka, the lack of a definite increasing trend suggests that the persistent increase in Corg and CaCO3 during the early Meghalayan Age was mainly driven by higher productivity during the winter season coupled with better preservation in the sediments. Both the intervals (3.0–3.5 ka and the last millennium) of nearly constant carbon burial coincide with a steady sea-level. The low carbon burial during the last millennium is attributed to the weaker-upwelling-induced lower productivity.

The present paper is an announcement of first absolute age dating directly on fossilized bones and teeth of the Pleistocene mammalian fauna from the Manjra valley, District Latur, Maharashtra, India. The fossilized samples were measured using the AMS facility at Inter-University Accelerator Centre, New Delhi, India. The results gave the time frame of 21,423 BP to 24,335 BP that correspond close to and the threshold of LGM and sheds important light on the palaeoecology of the area that supported diverse megafaunal species in the Upper Manjra valley. These calendar dates not only have wider significance in terms of first ever approximate chronological frame for the Pleistocene fauna in Peninsular India but also offer methodological innovations especially when the adequate bioapatite is absent in the fossilized bones and teeth from the fossil record.

The interaction of a droplet with a swirling airstream is investigated experimentally using shadowgraphy and particle image velocimetry techniques. In swirl flow, the droplet experiences oppose-flow, cross-flow and co-flow conditions depending on its ejection location, the velocity of the airstream and the swirl strength, which results in distinct droplet morphologies as compared with the straight airflow situation. We observe a new breakup phenomenon, termed as ‘retracting bag breakup’, as the droplet encounters a differential flow field created by the wake of the swirler's vanes and the central recirculation zone in swirl airflow. A regime map demarcating the various modes, such as no breakup, vibrational breakup, retracting bag breakup and bag breakup modes, is presented for different sets of dimensionless parameters influencing the droplet morphology and its trajectory. In contrast to the straight flow, the swirl flow promotes the development of the Rayleigh–Taylor instability, enhancing the stretching factor in the droplet deformation process, resulting in a larger number of fingers on the droplet's surface. In order to gain physical insight, a modified theoretical analysis based on the Rayleigh–Taylor instability is proposed for the swirl flow. The experimental behaviour of droplet deformation phenomena in swirl flow conditions can be determined by modifying the stretching factor in the theoretical model.

This study is on the absolute age dating of a multicultural site of Erenda, East Medinipur district, in coastal West Bengal, India. Charcoal samples were collected and measured using the accelerator mass spectrometry (AMS) facility at the Inter-University Accelerator Centre, New Delhi, India. These samples were collected from secured stratigraphic context of two excavated trenches. A careful collection of samples from two trenches provided us with the first calendar dates, 950 BCE and 1979 BCE, of protohistoric sites in coastal West Bengal. These calibrated calendar dates not only have wider significance in terms of archaeology but also methodological implications to understand the relevance of application of AMS from the dynamic coastal landscape in the humid tropics during the late Holocene period.

Accelerator mass spectrometry (AMS) activities at the Inter-University Accelerator Centre (IUAC) in New Delhi, India, started with its 15UD Pelletron accelerator and cosmogenic radionuclide (CRN) measurements of 10Be and 26Al. Realizing the demand of a radiocarbon (14C) AMS facility in India, a 500kV Pelletron accelerator based AMS system was installed in 2015. This facility was designated with the lab code IUACD for 14C measurements. 14C dates measured in 2015 and 2016 were published in the first radiocarbon date list (see text for details). The present list is the second 14C date list and consists of dates measured from January to December 2017.