Applications of Sentinel-2 satellite data for spatio-temporal mapping of deep pools for monitoring the riverine connectivity and assessment of ecological dynamics: a case from Godavari, a tropical river in India (2016-2021).

Rivers are dynamic ecosystems with diverse habitats that require ample connectivity to ensure the flow of ecosystem services, thus empowering the sustainable development of an entire basin. Geo-spatial tools offer powerful prospects for monitoring of aquatic ecosystems. The usefulness of Sentinel-2 datasets to assess river connectivity has been explored for an un-gauged seasonal river system. The present study was undertaken in five ecologically unique river reaches viz. Wainganga, Wardha, Pranhita, Godavari-mid and Manair in Godavari Basin in the Indian Deccan Plateau to map water spread dynamics at various time scales, i.e., fortnightly, monthly, seasonal, annual and demi-decadal during 2016-2021. The maximum value of perennial water spread per square kilometre of total floodplain area (2016-2021), determined using Sentinel-2 imageries, was observed in river Wardha (0.18) followed by Pranhita (0.12) and Wainganga (0.11). The water spread showed a decreasing trend, while the number of patches in the river corridor increased over time from post-monsoon to pre-monsoon season. The copious perennial habitat with relatively larger patches, incessant flow in river Pranhita and obstructed flow, large-sized patches reported in river Wardha during summer months, hold importance in terms of providing refuge to aquatic biota. This study provides evidence for the impact of water projects on spatio-temporal water spread dynamics in Godavari Basin. The demonstrated utility of Sentinel-2 imagery coupled with gauge station measurements for river continuity assessment and deep pool mapping would aid in enhancing our understanding on environmental flow at a spatial scale, which in turn would aid in effective river management to achieve the Sustainable Development Goals. The implications of this study for sustainable environmental management and limitations are also discussed.

Biplane double supported screw fixation for femoral neck fracture in young adults: A prospective cohort study.

Introduction: Achieving accurate anatomic reduction and stable internal fixation is mandatory in the management of femoral neck fractures (FNF) in adults. The spatial configuration and direction of the screws have been reported to provide stability to the fracture. The study's goal is to analyse the clinico-radiological outcome of the newer biplane double-supported screw fixation (BDSF) technique in the Indian cohort. Materials and methods: Patients with isolated FNFs underwent osteo-synthesis by BDSF technique. Radiological outcome was evaluated by time to union and fracture healing on plain radiographs. Clinical outcome was measured using the Harris hip score (HHS) at 1, 3, 6, and 12 months after surgery. The pain reduction was measured using the VAS score. Results: Twenty-seven patients with a mean age of 37.33 ± 9.84 years (24-55 years) were followed up for at least 12 months (12-31 months). The mean HHS at 12 months was 94.81 ± 8.18 (range: 68-100). Twenty-five patients were able to achieve radiological union within a mean time of 14.60 ± 4.69 weeks (range: 8-28). The overall complication rate was found to be 18.51% (5 out of 27 patients). Individual complications were non-union (2 patients; 7.4%), AVN (3 patients; 11.11%), and screw back out with femoral neck shortening (4 patients; 14.81%). Conclusion: Screw configuration using the BDSF technique provides a good union rate with minimum complications. The majority of patients resulted in a good (HHS >80) to excellent functional outcome. Based on the clinico-radiological outcome obtained, we conclude that this technique is effective in the fixation of FNF in adults. Level of study: Level II.

Heat transfer enhancement using CO2 in a natural circulation loop.

The natural circulation loop (NCL) is a highly reliable and noise-free heat transfer device due to the absence of moving components. Working fluid used in the natural circulation loop plays an important role in enhancing the heat transfer capability of the loop. This experimental study investigates the subcritical and supercritical heat transfer performance of a natural circulation loop (NCL) with CO2 as the working fluid. Operating pressures and temperatures are varied in such a way that the loop fluid should remain in the specified state (subcooled liquid, two-phase, superheated vapor, supercritical). Water and methanol are used as external fluids in cold and hot heat exchangers for temperatures above zero and below zero (in °C) respectively, depending on operating temperature. For loop fluids, the performance of CO2 is compared with water for above zero and with brine solution for the subzero case. Further, the impact of loop operating pressure (35-90 bar) on the performance of the system is also studied. For hot heat exchanger inlet temperature (5 to 70 °C) and cold heat exchanger inlet temperature (-18 to 32 °C), it was observed that the maximum heat transfer rates in the case of subcritical vapor, subcritical liquid, two-phase and supercritical CO2 based systems are 400%, 500%, 900%, and 800% higher than the water/brine-based system respectively.