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The current paper presents the development and characterization of polyvinylidene fluoride (PVDF)-Zn2GeO4 (ZGO) fine fiber mats. ZGO nanorods (NRs) were synthesized using a hydrothermal method and incorporated in a PVDF solution to produce fine fiber mats. The fiber mats were prepared by varying the concentration of ZGO NRs (1.25–10 wt %) using the Forcespinning® method. The developed mats showed long, continuous, and homogeneous fibers, with average fiber diameters varying from 0.7 to 1 µm, depending on the ZGO concentration. X-ray diffraction spectra depicted a positive correlation among concentration of ZGO NRs and strengthening of the beta phase within the PVDF fibers. The composite system containing 1.25 wt % of ZGO displayed the highest piezoelectric response of 172 V. This fine fiber composite system has promising potential applications for energy harvesting and the powering of wearable and portable electronics.

Materials that show superior light-emitting and catalytic properties are in high demand among the scientific community owing to their applications in the areas of optoelectronics and (opto)electrocatalysis. In this work, we have synthesized sub-10-nm Pr 2 Sn 2 O 7 (PSO) and Pr 2 Sn 2 O 7 :Bi 3+ (PSOB) nanoparticles (NPs) and investigated their optical and electrochemical properties. On ultraviolet irradiation, PSO NPs display blue emission because of the presence of oxygen vacancies. Interestingly, PSOB NPs have higher blue emission intensity than undoped PSO NPs owing to the increase in oxygen vacancy defect density induced by Bi 3+ doping. Moreover, PSOB NPs display higher efficiency in terms of current density than PSO NPs as a catalyst toward the oxygen evolution reaction (OER). The kinetic OER models of PSO and PSOB NPs are quite different as displayed by their different Tafel slopes. Interestingly and as another advantage, the PSOB sample is more conducting with low impedance value than the PSO counterpart. With all these advantages due to high oxygen vacancies induced by Bi 3+ doping, PSOB NPs have a great potential to be used as blue phosphors, charge storage devices, and capacitors.

The distribution, enrichment, and ecotoxicity potential of Bangladesh part of Sundarban mangrove was investigated for eight trace metals (As, Cd, Cr, Cu, Fe, Mn, Pb, and Zn) using sediment quality assessment indices. The average concentration of trace metals in the sediments exceeded the crustal abundance suggesting sources other than natural in origin. Additionally, the trace metals profile may be a reflection of socio-economic development in the vicinity of Sundarban which further attributes trace metals abundance to the anthropogenic inputs. A total of eleven surficial sediment samples were collected along a vertical transect along the freshwater–saline water gradient. The sediment samples were digested using EPA 3051 method and were analyzed on ICP-MS. Geo-accumulation index suggests moderately polluted sediment quality with respect to Ni and As and background concentrations for Al, Fe, Mn, Cu, Zn, Pb, Co, As, and Cd. Contamination factor analysis suggested low contamination by Zn, Cr, Co, and Cd, moderate by Fe, Mn, Cu, and Pb while Ni and As show considerable and high contamination, respectively. Enrichment factors for Ni, Pb, and As suggests high contamination from either biota or anthropogenic inputs besides natural enrichment. As per the three sediment quality guidelines, Fe, Mn, Cu, Ni, Co, and As would be more of a concern with respect to ecotoxicological risk in the Sundarban mangroves. The correlation between various physiochemical variables and trace metals suggested significant role of fine grained particles (clay) in trace metal distribution whereas owing to low organic carbon content in the region the organic complexation may not be playing significant role in trace metal distribution in the Sundarban mangroves.

Delafossite materials demonstrate multifunctional applications due to their excellent catalytic properties, which vary depending on their morphology, particle size, and synthetic method. Herein, a few novel applications of the delafossites are reported, which can be implemented in commercial, medical, and domestic settings. In the present work, we are presenting two different delafossites, CuGaO 2 and CuFeO 2 nanoparticles, and their composite with cotton fiber. Multifunctional cotton fabric is prepared by depositing a uniform coating layer of CuGaO 2 and CuFeO 2 and exhibits excellent photocatalytic self-cleaning, UV blocking, antimicrobial activity, and hydrophobicity. CuGaO 2 and CuFeO 2 nanoparticle concentrations of 1 mM and 2 mM were deposited over the cotton fabric using citric acid as a binder by a simple sonication method. Surface analysis, bindings, stability, stain resistance, and UV blocking characteristics of the functionalized cotton fabric are performed by SEM, EDX, XRD, FTIR, and UV–Vis spectroscopy. Both CuGaO 2 -cotton and CuFeO 2 -cotton exhibit excellent photocatalytic activity, which is evident from the UV–Vis spectroscopic analysis after mixing with methylene blue dye and subsequent exposure to simulated solar light. In addition, CuGaO 2 -cotton and CuFeO 2 -cotton block most of the harmful UV radiation, 95–97.5% (approx.) in the case of CuGaO 2 and 90% (approx.) in the case of CuFeO 2 . The modified cotton fabrics present good antimicrobial activity against gram-positive and gram-negative bacteria, which is confirmed by antimicrobial tests with Staphylococcus aureus and E. coli bacteria. The newly fabricated cotton-delafossite composite, with all its promising applications, can be viewed as a valuable, sustainable contribution of materials science to humanity. Graphical Abstract

Materials that show superior light-emitting and catalytic properties are in high demand among the scientific community owing to their applications in the areas of optoelectronics and (opto)electrocatalysis. In this work, we have synthesized sub-10-nm Pr 2 Sn 2 O 7 (PSO) and Pr 2 Sn 2 O 7 :Bi 3+ (PSOB) nanoparticles (NPs) and investigated their optical and electrochemical properties. On ultraviolet irradiation, PSO NPs display blue emission because of the presence of oxygen vacancies. Interestingly, PSOB NPs have higher blue emission intensity than undoped PSO NPs owing to the increase in oxygen vacancy defect density induced by Bi 3+ doping. Moreover, PSOB NPs display higher efficiency in terms of current density than PSO NPs as a catalyst toward the oxygen evolution reaction (OER). The kinetic OER models of PSO and PSOB NPs are quite different as displayed by their different Tafel slopes. Interestingly and as another advantage, the PSOB sample is more conducting with low impedance value than the PSO counterpart. With all these advantages due to high oxygen vacancies induced by Bi 3+ doping, PSOB NPs have a great potential to be used as blue phosphors, charge storage devices, and capacitors.

On-orbit assembly is an enabling technology for many space applications. However, current methods of human assisted assembly are high in cost and risk to the crew. Thus, there is a desire to automate the on-orbit assembly process using robotic technology. Automation introduces additional challenges in the design of the assembly, particularly within the control systems. During an assembly sequence, an assembler robot can undergo multiple reconfigurations of its geometry and dynamics as it attaches to and releases from individual modules. The particular problem addressed in this thesis is how to account for mass and stiffness property variations that occur with changes in configuration. Proper model generation for each configuration is critical to maintain control system stability and efficiency. This thesis explores two specific challenges associated with this problem: (1) the design of a model generation architecture to where module mass property information is known, but specific configurations are unknown; and (2) the selection of a model generation architecture that is appropriate for a given assembly architecture.Literature review of the possible model generation architectures revealed a gap in the literature, when models are aggregated online based on module mass property information. The challenge is resolved through the design of an architecture, called Online Model Calculation. Online Model Calculation uses module information obtained at the time of attachment to generate the model for the current configuration online. This is accomplished through the parameterization of the control algorithms with respect to a property vector. The property vector contains mass property information (ex. mass, inertia) that is used to generate the model. The design of Online Model Calculation, both in terms of framework and algorithm parameterization, is successfully implemented and validated on hardware. Results show a tracking error performance improvement when the correct model of the system is used in the control system over an unupdated model of the assembler along. Online Model Calculation balances a priori knowledge about the possible configurations with identification of the model online.The challenge of selecting a model generation architecture is accomplished through the development of a process that downselects feasible architectures into a single optimal architecture. This process is based on a set of generalized, quantitative metrics that are used to compare architectures from the perspectives of the control system, spacecraft, and assembly operation levels. It is exercised on three case scenarios, using a simulation tool that is developed to evaluate the model generation architecture metrics for a given assembly architecture. Results clearly show that for different assembly scenarios, different model generation architectures perform best. The quantification of this performance difference and the process for selecting the appropriate architecture constitute a key contribution of this work.

Reconfiguration is an important characteristic in furthering on-orbit servicing, assembly, and operations. Previous work has focused on large assemblers manipulating small payloads, where the dynamics of the assembler is not significantly changed. This work seeks to identify the impact of reconfiguration on maneuver performance. Reconfiguration is considered in two categories: implementation and application. Implementation of reconfiguration consisted of developing a method for defining and updating a configuration, implementation on the SPHERES testbed, and execution of tests (in simulation and on the International Space Station) to assess the control performance improvement after reconfiguration.Four applications were considered in this work, two hardware applications and two systems applications modeled through simulation. The objective of the SWARM application was to demonstrate autonomous assembly capability through docking and undocking maneuvers. The objective of the SIFFT application was to demonstrate formation reconfiguration capability, through the expansion and rotation of an equilateral triangle of three satellites.The objective of the systems applications was to determine the impact of re-configuration in a larger mission context. One application, Mass Property Update, considered how the choice of method for obtaining the mass property information impacts operations. The other application, Modularity Analysis, considered how the implementation of modularity is driven by the mission objectives.Overall, this work has served to demonstrate the control impact of reconfiguration though implementation on the SPHERES testbed. This implementation was used on two hardware applications to determine the performance of reconfiguration for assembly and formation reconfiguration missions. Also, the impact of reconfiguration has been studied in the broader systems context. The choice of method of mass property update was demonstrated to have an impact on operations, in terms of reliability and mass. Finally, the method incorporation of modularity for purposes of on-orbit servicing and assembly was demonstrated to be driven by mission design parameters.

Wetlands are one of the most productive ecosystems and play a significant role in the ecological balance. The Kabar Tal (86° 05' E to 86° 09' E, 25°30' N to 25° 32') wetland is the largest freshwater lake in Northern Bihar. Owing to anthropogenic pressures the sediment and water quality of Kabar Tal has been adversely affected. In order to study the distribution of trace metals, twenty five (25) surface sediments were analysed. The average concentration of trace metal in sediments followed the trend Fe>Mn>Pb>Ni>Co>Cu>Cd. For assessing the degree of pollution in Kabar Tal sediments concentration factor (CF), enrichment factor (EF), geo-accumulation index (I^sub geo^) and pollution load index (PLI) were calculated. These indexes indicate that Kabar Tal is extremely contaminated with respect to Cd. The PLI value indicates that the lake is polluted. In addition, the sequential extraction of sedimentary phosphorus was performed for different fractions of Phosphorus as Non-Apatite Inorganic Phosphorus (NAIP), Apatite Phosphorus (AP), Inorganic Phosphorus (IP) and Organic Phosphorus (OP) representing the different pools in the Kabar Tal sediments. The fractions of phosphorus in the sediment samples were found quite low as NAIP 72 ± 108.05 mg/Kg, AP 19.94 ± 16.805 mg/Kg, IP 25.56 ± 23.23 mg/Kg and OP 40.86 ± 47.66 mg/Kg. The results reflect spatial variability and followed the order NAIP>OP>IP>AP. NAIP was the dominant fraction in Kabar Tal and bioavailable poolfor the uptake by aquatic flora.

The Mars 2020 (M2020) Mission carrying Perseverance, the most advanced rover ever sent to Mars, successfully launched on an Atlas V 541 (AV-088) launch vehicle from the Eastern Test Range (ETR) at Cape Canaveral Air Force Station (CCAFS) in Florida at 11:50:00 UTC (T-Zero time) on July 30, 2020. After some station reconfiguration, carrier/telemetry were locked at both Deep Space Network (DSN) Canberra and Goldstone stations. Perseverance entered the Martian atmosphere at 20:36:50 Spacecraft Event Time (SCET) UTC, and landed inside Jezero Crater at 20:43:49 SCET UTC on February 18, 2021. Confirmation of nominal landing was received at the DSN Goldstone and Madrid tracking stations via the Mars Reconnaissance Orbiter at 20:55:11 Earth Received Time (ERT) UTC. This paper summarizes in detail the actual vs. predicted performance in terms of launch vehicle events, launch vehicle injection performance, actual DSN spacecraft lockup,\\r trajectory correction maneuver performance, Entry, Descent, and Landing events, and overall trajectory and geometric characteristics.

Crop growth and productivity has largely been vulnerable to various abiotic and biotic stresses that are only set to be compounded due to global climate change. Therefore developing improved varieties and designing newer approaches for crop improvement against stress tolerance have become a priority now-a-days. However, most of the crop improvement strategies are directed toward staple cereals such as rice, wheat, maize etc., whereas attention on minor cereals such as finger millet [ (L.) Gaertn.] lags far behind. It is an important staple in several semi-arid and tropical regions of the world with excellent nutraceutical properties as well as ensuring food security in these areas even during harsh environment. This review highlights the importance of finger millet as a model nutraceutical crop. Progress and prospects in genetic manipulation for the development of abiotic and biotic stress tolerant varieties is also discussed. Although limited studies have been conducted for genetic improvement of finger millets, its nutritional significance in providing minerals, calories and protein makes it an ideal model for nutrition-agriculture research. Therefore, improved genetic manipulation of finger millets for resistance to both abiotic and biotic stresses, as well as for enhancing nutrient content will be very effective in millet improvement. Apart from the excellent nutraceutical value of finger millet, its ability to tolerate various abiotic stresses and resist pathogens make it an excellent model for exploring vast genetic and genomic potential of this crop, which provide us a wide choice for developing strategies for making climate resilient staple crops.