Though various two-dimensional (2D) materials have been identified as useful candidates for piezoresistive pressure sensors, layered vanadium pentoxide (V2O5) has been negligibly explored. Here, simple drop cast films of ultrasonicated V2O5 on copper (Cu) substrates, stacked face-to-face, are demonstrated to exhibit remarkable piezoresistive pressure sensing behaviour over a pressure range of 250-2000 Pa, as impacted by the growth of copper oxide (CuO) at V2O5/Cu interface. Significant and accelerated growth of CuO at the interface, in ambient conditions, was observed with the addition of deionized (DI) water in the solvent used for drop casting V2O5 films, while it was negligible for those deposited without DI water. The strong growth of CuO interface layer in the former, attributed to the enhanced interaction between V2O5 and Cu in the acidic medium provided by DI water, was found to induce microcracks in V2O5 films. These microcracks could be causing reduced sensitivity of the pressure sensors (similar to 0.36 kPa(-1)) with these films, compared to the sensors with films deposited without DI water (similar to 2.57 kPa(-1)). The results suggest the tunable pressure sensing performance of V2O5 films owing to their readiness to transfer electrons with other materials. In-situ impedance spectroscopic measurements under an applied pressure are also demonstrated, which revealed the major contribution of V2O5/V2O5 interface on sensor response, thereby offering insight into the sensing mechanism. Additionally, V2O5 films are demonstrated as flexible pressure/strain sensors for detecting human physiological activities like finger bending, blinking, swallowing etc.

This study presents the synthesis of single-phase 2H-MoSe2 and one-pot synthesis of MoSe2/rGO (MSR) composite used for the detection of environmental pollutants (NO2, NH3, H2S CO2, CO, CH4, CH3COCH3) at ambient temperature (similar to 25 degrees C). The gas sensing devices were fabricated on Ti/Pt interdigitated electrodes with different compositions of MSR composite viz. 10 (MSR-10), 20 (MSR-20), and 30 (MSR-30) weight % of rGO. The sensitivity of the p-type MoSe2, rGO and MSR-20 was calculated to be similar to 29 %, similar to 24 % & similar to 38 %, respectively at 4 ppm concentration of NO2. The respective response and recovery time were calculated to be 191/218 s, 225/412 s, and 110/128 s for MoSe2, rGO, and MSR-20 composite at 4 ppm of NO2 gas. The response curve at the lowest detection limit indicates stable performance of the device, which makes it suitable for its real-time application. The response time and recovery time of the composite device are 40 s and 65 s, respectively at 100 ppb concentration of NO2 gas. The sensing device was subjected to 0.1 ppm to 4 ppm of NO2 gas concentration, and the obtained device response was highly repeatable and stable after 60 days. The possible gas sensing mechanism based on charge transfer is proposed for fabricated devices using MSR composite material. The gas sensing device parameters, selectivity, repeatability, sensitivity, and stability show a great potential of MoSe2-rGO composite material in gas sensing.

We report highly selective and reliable room temperature H2 sensing using TiO2-PdO heterostructure thin film based chemiresistive sensors in comparison with PdO thin film sensor. Gas sensing studies show higher sensitivity and better selectivity towards H2 gas in the range 0.1 %-1% for TiO2-PdO heterostructure thin film sensor compared to PdO sensor. Based on gas analysis results of the surface species formed, H2 sensing mechanism is suggested. Temperature dependance of sensor response, repeatability, reproducibility, long term stability and humidity dependence studies at room temperature on TiO2-PdO sensor show satisfactory performance promising viability for portable, hand held H2 sensors. In addition to the advantages of heterostructure for better gas selectivity, increase in selectivity for room temperature sensor is shown using transient impedance measurements at characteristic frequency related to the target gas. Study suggests applying characteristic frequency measurements as a superior technique for obtaining high selectivity for portable H2 sensor.

Herein, we present interdigitated microelectrode nitrogen dioxide (NO2) gas sensor by utilizing layered nanosheets of tungsten diselenide (2H-WSe2) intercalated with reduced graphene oxide (rGO). The 2H-WSe2 nanosheets and its composite with rGO were prepared through simple solvothermal process, resulting in intercalation with rGO sheets. Comprehensive investigation of gas-sensing properties of WSe2-rGO (WSR) composite nanosheets with their high selectivity and sensitivity to NO2 detection at ambient temperature have been performed. The WSR sensor achieved notable responses of similar to 2.9%, similar to 25.9%, and similar to 39% at NO2 concentrations of 50 ppb, 1 ppm, and 4 ppm, respectively. Furthermore, the sensor efficiently maintained good response of similar to 30.8% to NO2 gas even after 210 days of testing, demonstrating its outstanding long-term stability.

ZnO-incorporated NBS glasses have been studied for their application as a matrix for nuclear waste immobilization. However, structural factors affecting chemical durability have not been established. In this study, the structural changes in NBSZn glasses across various Na2O/(B2O3 + ZnO) ratios are explored using multinuclear MAS, MQMAS NMR, and EXAFS techniques. The Na MAS and MQMAS studies reveal remarkable changes in the Na environment after ZnO incorporation, which leads to an increase in chemical durability. Based on the results from NMR and EXAFS, we rationalized the structure of this glass in terms of the modified random network (MRN) model. The glass network comprises a highly polymerized region and alkali percolation channels bordered by nonbridging oxygens from the depolymerized regions. The constriction of these percolation channels increases the chemical durability of the glass. Our findings will help in the advancement of Zn-containing NBS glasses as a promising matrix for nuclear waste immobilization.

Realizing a single step synthesis protocol for conducting the Cu0.87Se phase in nanosheet form deals with an exciting yet unmapped target demanding a simple procedure. In this pursuit, the current study defines a molecular template approach for hexagonal phase Cu0.87Se nanosheets (NSs) by heat-up of a new and structurally characterized precursor, {Cu(2-SeC4H3N2)}4, in oleylamine (OAm), while agglomerated cubic phase Cu1.8Se nanoparticles (NPs) was produced when the same precursor was pyrolyzed. Subsequently, both the precursor and the nanostructures were identified by a number of characterization tools such as single crystal/powder X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS). Moreover, all the nanostructures were evaluated for their prospects as catalysts for water splitting. Furthermore, periodic density functional theory (DFT) studies were performed to explore the catalytic water oxidation reaction over the Cu0.87Se and CuSe surfaces along with the restructured CuO surface.

Bulk SnSe and SnSe2, with direct-band gaps of 1.3 eV and 1.84 eV, are promising materials for optoelectronics, lithium-ion batteries, thermoelectrics, and supercapacitors, due to their excellent electrochemical performance for energy storage. In this context, a new molecular precursor, [Me2Sn(SeC4H3N2)2], has been derived from bis(2-pyrazinyl)diselenide {(2-pyzSe)2} and structurally characterised by single crystal X-ray diffraction (sc-XRD) that serves as a building block for the fabrication of tin selenide (SnSe) nanosheets and tin selenide/g-C3N4 composites. The electrochemical performance of the synthesised nanosheets and composites was evaluated for their potential use in supercapacitor applications. The band gaps of rectangular SnSe (1.85 eV) and hexagonal SnSe2 (2.21 eV) nanosheets, and tin selenide/g-C3N4 composites (1.89 and 1.91 eV) exhibited a blue shift compared to those of bulk SnSe (Eg = 1.3 eV) and SnSe2 (Eg = 1.84 eV). The tin selenide/g-C3N4 composite utilised in supercapacitor applications exhibited a specific capacitance of 140 F g-1 at a current density of 1 A g-1. Remarkably, it retained 85% of this specific capacitance after 5000 cycles, demonstrating outstanding cycling durability.

Copper sulfide nanostructures have attracted significant attention in green energy technologies owing to their earth-abundant nature and promising optoelectronic properties. In this study, we report a reproducible, phase-selective synthesis of nanocrystalline copper sulfides, namely, diginite (Cu1.8S) and covellite (CuS), via low-temperature thermolysis of a newly synthesized two-dimensional (2D) copper thiolate coordination polymer: [(PEt3)2Cu2(4-Spy)2] n ( 2D-CuSpy ) as a single-source molecular precursor. The precursor undergoes facile thermal decomposition to yield copper sulfide nanoparticles under mild conditions. Comprehensive characterization using powder X-ray diffraction (pXRD), electron microscopy, and diffuse reflectance spectroscopy confirms the phase purity, morphology, and tunable bandgap (1.8-2.1 eV) of the resulting nanostructures. Notably, the solvent choice was found to significantly influence the phase and morphology of the final products. Prototype photoelectrochemical cells fabricated with the pristine nanomaterials demonstrated excellent photocurrent response and rapid photoswitching behavior, highlighting their potential as alternative photon-absorbing materials for sustainable energy conversion.

We describe the 60Co-Gamma radiolytic synthesis of stable poly(bis[2-(methacryloyloxy)ethyl] phosphate) (PB2MEP) -decorated gold nanoparticles (PB2MEP-Au) for spectrophotometric detection of uranium (U(VI)) in the ppb level. The developed technique is based on the Localize Surface Plasmon Resonance (LSPR) band intensity quenching, accompanied by a red shift in the wavelength range 523-545 nm at higher concentrations, due to interaction between U(VI) ion and phosphate group bearing PB2MEP-Au. The response was linear in the 5-80 ppb U(VI) concentration range, with LOD of 8.6 ppb. Samples were characterized by transmission electron microscopy, Particle Size Analysis and Zeta Potential measurements to determine morphological transitions upon analyte interaction. Density Functional Theory (DFT) calculations were invoked to study the Au nanoparticle stabilization mechanism, and revealed the interaction of U(VI) with PB2MEP-Au to be thermodynamically spontaneous for the formation of [UO2(B2MEP)2(H2O)]2+ complex, the stability primarily driven by entropy. Interference by other coexisting metal ions was negligible up to interferent:target ratios of 10:1. The method was validated through quantification of U(VI) in water samples spiked with known U(VI) concentrations, the results being in corroboration with those reported using laser fluorimetric method. A T-test confirmed the results derived from the proposed method were not significantly different from those obtained using the standard estimation protocol at a 95% confidence level.

Magnesium-magnesium hydride (Mg-MgH2) system has attracted attention worldwide recently because of its simple hydrogenation-dehydrogenation process, the cost-effectiveness of the raw materials, and relatively high hydrogen storage capacity compared to the other metal-metal hydride systems. The present study deals with the optimization of the process parameters for the synthesis of magnesium hydride (MgH2) in sizable quantities using commercial-grade magnesium powder, characterization with respect to hydrogen storage capacity, by thermal dehydrogenation and pH-controlled aqueous hydrolysis. The thermal hydrogenation-dehydrogenation and mild acidified aqueous dehydrogenation behaviour of MgH2 were studied systematically to compare the decomposition kinetics and storage capacity. The superior catalytic effect of V2O5 on decreasing the onsetdehydrogenation temperature of MgH2 is demonstrated. The MgH2-5 wt. % mesoporous V2O5 sample starts releasing hydrogen at 220 degrees C, which is substantially less than the as-synthesized un-catalysed MgH2 under identical conditions which starts releasing hydrogen at 430 degrees C. The dehydrogenated MgH2-5wt. %V2O5 could be completely re-hydrogenated at 150 degrees C. Hydrolysis of as-synthesized MgH2 was demonstrated using an aqueous solution using tartaric acid and the dehydrogenation behaviour was co-related with the pH of the solution. More than 90% hydrogen yield was achieved by the hydrolysis of MgH2 in a tartaric acid solution of pH-4. Based on the result, a hydrogen gas dispenser using solid-state magnesium hydride as a hydrogen source is proposed for laboratory applications for the supply of ultra-pure hydrogen for various reactions and crystal growth experiments.

Metal oxide nanomaterials hold a dominant place in gas sensor field owing to their ample availability, ease of synthesis, viability for portable applications, compatibility with IoT and so on. Nevertheless, there is a constant pursuit to improve their selectivity towards the target gas and reduce the operating temperature. Doping of metal oxide nanomaterials with transition metals has proved successful in many applications. In this context, we report on the simple and cost effective synthesis of Pd doped ZnO (PdZnO) films by SILAR method and their potential application as H2S sensor, operating at room temperature. Both ZnO and PdZnO films were extensively characterized by XRD, FESEM, AFM and XPS to confirm the phase purity, morphology, Pd incorporation etc. Gas sensing studies showed that compared to pure ZnO films, PdZnO films exhibited fast, reversible, selective and excellent response to H2S (similar to 8 times change in conductivity for 20 ppm) at room temperature. Further the sensor demonstrated stable operation in the relative humidity range from 40 % to 75 %. Negative capacitance exhibited by impedance measurements substantiated the relaxation of interface states upon H2S exposure. Based on the experimental results and DFT simulation studies, a plausible sensing mechanism is discussed. Straightforward fabrication process and room-temperature operation project PdZnO sensors appealing for low cost, portable H2S sensing applications.

Dhruva is a 100MWth Research Reactor utilized for the production of radioisotopes, and offer irradiation facilities for testing various materials such as nuclear fuel & structural materials. During normal operation, the primary cooling is achieved by circulation of Heavy Water through Main Coolant Pumps (MCPs) and the secondary and tertiary cooling is achieved by Process Water Pumps (PWPs) and Sea Water Pumps (SWPs). However, on power failure or outage of pumps, Heavy Water is circulated through core by means of Auxiliary Coolant Pumps (ACPs). Each of the ACPs has two prime movers- one water driven turbine and an electric motor on class-II supply. Various process interlocks for the operations viz. opening/closing of valves, starting/stopping of motors etc. are controlled by a hardwired electronic based system called Emergency Cooling System Logic (ECS Logic). The ECS Logic System is classified as Class-IA system. There are three identical but totally independent channels in ECS Logic System. The outputs of three channels are used in a ladder network to obtain two-out-of-three logic which is then used to actuate appropriate valves and motors. To monitor the health of ECS logic in an online mode, an independent test and monitoring system in the form of Fine Impulse Testing (FIT-ECS) is also deployed. To take care of aging & obsolesces in ECS Logic, upgradation of ECS Logic System was taken up. The new ECS channels have the same inputs/outputs/logic implementation and use circuits & components identical to old ECS channel. Interface to existing FIT-ECS System is kept same as earlier. However, the numbers of cards were reduced and unused components of the functions not utilized in old boards were deleted. New ECS Logic has PCB based backplane, Euro connectors for card to backplane connection and IDC on backplane for Field I/O interface. These modifications in the upgraded system were incorporated to achieve high reliability and availability. For new ECS Logic, Mean Time Between Failure (MTBF) and Probability of Failure per Hour (PFH) have been calculated to be 1,79,985 h and 2.414E-07 h−1 respectively, considering MTTR of 8 h, proof test interval of 1 month and no diagnostic coverage. The paper provides detailed account of the upgradation of the ECS logic, its salient features, advantages gained, qualification tests performed & its results, methodology of testing & commissioning of the system and performance of the system.

In this paper, thick, metallic bright electrodeposited tungsten rich Ni-W-P alloy coatings with two different compositions Ni-36.3wt%W-3.3wt%P (designated as Ni-W-LP) and Ni-19.5wt%W-7.7wt%P (designated as Ni-W-HP) were chosen for comparison of heat-treatment dependent evolution of crystal structure, grain growth, nanohardness and tribological properties with respect to Ni-50.7wt%W coating. The systematic temperature dependent evolution of crystal structure and phases from as-deposited amorphous alloys were mapped using insitu high temperature GIXRD investigation and peak-broadening analysis. Subsequent variation of nanohardness/microhardess was measured. Detailed tribological investigation of both as-deposited and heat-treated coatings was done by ball-on-plate dry sliding experiment and the observed coefficient of friction and wear data were correlated with measured nanohardness, H/E and H3/E2 ratio and a wear mechanism was proposed based on detailed FESEM investigation of wear scars.

Sodium manganese oxides are regarded as a valuable class of cathode materials for sodium-ion batteries. By varying the stoichiometry of Na, Mn and O, it is possible to obtain layered, tunnel and spinel type structures, which can withstand the electrochemically-triggered sodiation-desodiation process. In this work, we report the electrochemical performance of Na4Mn2O5, a sodium-rich manganese oxide, which has been previously reported to suffer from structural instability due to the Jahn-Teller distortion of the Mn3+ ion. It was observed that the Na4Mn2-xZrxO5 (x = 0.1) cathode delivered a discharge capacity of similar to 203 mA h g-1 post 250 cycles with a capacity retention rate of similar to 82.8% on doping with Zr4+ ions. The improvement in cycling ability and rate capability is attributed to the enhanced structural stability and improved electronic conduction brought about by the substitution of Mn3+ by Zr4+ in Na4Mn2O5. Density functional theory-based studies were conducted, which adequately support the obtained results.

Non-lanthanide based NaBiF4 host have evoked remarkable interest due to unique luminescent property and potential applications. Current synthetic methods are not environment friendly and causes pollution. This is the first report mentioning green synthetic innovative route to develop upconversion, crystalline, and temperature sensing material. Here, we deigned ultrasonic assisted green approach for successful synthesis of beta-NaBiF4:Yb3+, Er3+ (size -25-100 nm) using Tabernaemontana divaricata leaves extract without any surfactant. Characterization techniques such as XRD, SEM, TEM, XPS, EDX, and PL unveiled its properties. Green and red upconversion emissions (lambda ex = 980 nm) were two-photon absorption process. The possible energy transfer and thermal quenching mechanism is discussed. Using thermally coupled levels (2H11/2 and 4S3/2) of Er3+, FIR based temperature sensing revealed Delta E -841 cm -1, linear response (R2 -0.99), outstanding relative sensitivity (Sr max similar to 1.4 % K-1 @294 K), good absolute sensitivity (Sa max similar to 0.29 %K-1 @ 398 K) and a low temperature resolution (delta Tmin = 0.35 K) over temperature range 294-398 K.

Lithium-sulphur batteries (LSBs) are a promising candidate for the next generation of high energy density, safe, green and affordable batteries but their practical utilization is hindered by several roadblocks including low cycle life, fast capacity fade, low sulfur utilization due to insulating nature of sulfur and “polysulfide shuttle”. This work employs multiple strategies to circumvent the aforementioned issues like utilizing (i) a reduced graphene oxide (rGO) conducting carbon framework for improving conductivity and mechanical stability of cathode, (ii) polyaniline conducting polymer with polar groups to restrain soluble lithium polysulfides (LiPS) by physisorption/chemisorption (iii) separator modification with graphene oxide to act as a second barrier layer to suppress LiPS migration and support the cathode current collector to enhance sulfur utilization. The combination of these strategies led to a LSB cell that exhibited high initial capacity, low capacity fade and improved lithium ion diffusion as well as lowered cell impedance. The synthesized cathode composite of PANI-rGO-sulfur (PGS) was characterized by several techniques like power x-ray diffraction, scanning electron microscopy, thermogravimetry etc. Electrochemical characterization of cells was performed by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic cycling. The coin cell delivered a superior initial capacity of 807 mAh/g at 100 mA/g current density. Upon cycling at a high current density of 1A/g it delivered a capacity of 478 mAh/g with excellent stability for 500 cycles and lower capacity fade of 0.02% per cycle.

Magnetic properties of Y0.67Sr0.33MnO3 (YSMO) and La0.67Sr0.33MnO3 (LSMO) thin films heterostructures (YSMO/LSMO) deposited on single-crystalline (001) SrTiO3 (STO), (001) LaAlO3 (LAO) and MgO substrates using pulsed laser deposition technique were investigated. Magnetization (M) vs. the applied field (H) measurements revealed shift in hysteresis loop showing the exchange bias effect of about 80 Oe for the heterostructures on LAO substrate, which was absent for those on STO substrates. In order to investigate this, single-layer LSMO layers were deposited on these substrates. X-ray diffraction patterns revealed significant compressive strain and a weaker tensile strain for LSMO films on LAO and STO substrates, respectively. Raman spectroscopy measurements further confirmed the lattice mismatch-induced strain in LSMO layer on LAO substrate. These different strain conditions in LSMO films on both the substrates are suggested to be contributing to the emergence of different magnetic ground states in these systems, which could be leading to pinning of spins at the interface and resulting in a significant exchange bias effect (EBE) on LAO substrate.

Human and environmental health is greatly affected due to toxic gas emissions in the environment from power generation, transportation and other industries. For real time monitoring of polluting gases, gas sensor should be reliable, robust and stable in all environmental conditions. We report, nanostructured PdO thin film based portable and low voltage (< 5 V) operating NO2 sensor for sensing sub-ppm level of NO2, with limit of detection (LOD) 80 ppb at room-temperature. To optimize the sensor response of PdO thin film prepared by cost effective self-assembly technique films were calcined at 200 degrees C, 300 degrees C and 400 degrees C. Effect of calcination temperatures on film's surface morphology, composition and energy band gap have been studied using various techniques. The charge carrier concentration, charge carrier transport mechanism, sensitivity, selectivity, repeatability, reproducibility, reliability, linearity etc. have been studied. PdO thin films calcined at 400 degrees C are most sensitive with approx. 60% and 100% response for 500 ppb and 1 ppm NO2, respectively at room-temperature. After stable response upto 6 months and more was obtained for these, a portable, pocket size electronic device of size (8 x 5 cm) was fabricated and tested successfully, coupling with the sensor film to prepare a wearable sensor.

Human and environmental health is greatly affected due to toxic gas emissions in the environment. Therefore, monitoring systems such as gas sensors are required to detect these toxic gases above certain safe threshold limiting value. Here we report a room-temperature operating sensor based on PdO thin film, a metal oxide semiconductor, made by very simple and cost-effective technique that can detect NO2 as low as 10 ppb. Depending on the methods of preparation of PdO thin films, these sensors were divided in three categories, sensor S1, S2 and S3. Structural, optical and morphological studies of PdO films have been carried out by various analytical techniques. Characteristics peaks belonging to tetragonal phase of PdO has been obtained from X-ray diffraction (XRD) pattern and the crystallite size estimated was10 nm. After depositing Au electrodes on PdO thin films, sensors were prepared and sensing characteristics were compared. Among the three types of sensors, the response of S1 was best and S3 was the most stable one. Temperature dependence studies showed that upto 40 C response increased. Sensor response on humidity variation was negligible. Based on impedance spectroscopy studies, types of charge transfer in nanocrystalline PdO films and their NO2 gas sensing mechanism were suggested.

Combination of natural polymer and nanoparticle has always been fascinating for biomedical applications. Here, we have demonstrated a simplified dessolvation-coprecipitation technique for the development of gelatin grafted Fe3O4 magnetic nanoparticles (Gel-MNPs), and investigated their potential applications in drug delivery and hyperthermia therapy. XRD, TEM, FTIR, TGA and light scattering techniques were used to confirm the phase formation of core Fe3O4 MNPs and their successful surface modification with gelatin moieties. The Gel-MNPs showed good aqueous colloidal stability and pH dependent surface charge characteristics. The hydrophobic anticancer agent, curcumin was employed as a model drug to investigate the loading and release properties of Gel-MNPs. A loading efficiency of about 95% was achieved at drug to particle ratio of 1:10 and curcumin loaded Gel-MNPs (Cur-Gel-MNPs) exhibited pH dependent release behaviour of loaded drug with higher release at mild acidic environment. These Cur-Gel-MNPs have shown dose dependent cytotoxicity towards lung (A549) and breast (MCF-7) cancer cell lines. Further, CUR-Gel-MNPs exhibited enhanced heat activated killing of cancer cells under AC magnetic field, suggesting their usefulness for magnetic hyperthermia therapy.