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Optimized trimetallic CoNiFe phospho-boride electrocatalyst for overall seawater electrolysis
Utilizing abundant seawater for hydrogen production by electrolysis poses new challenges to electrocatalyst performance, demanding effectiveness, resilience, and selectivity for oxygen evolution reactions (OER) over undesired reactions in harsh saline conditions. Herein, trimetallic phospho-boride, CoNiFePB, was synthesized via a chemical reduction method by carefully tuning the concentrations of all elements for overall seawater splitting. The optimized CoNiFePB demonstrated superior OER activity, requiring only 239 mV to achieve 10 mA/cm2 in alkaline simulated seawater, outperforming bimetallic configurations (CoNiPB and CoFePB). The enhancement in hydrogen evolution reaction (HER) activity was attained by adjusting the B/P molar ratio in CoNiFePB, resulting in a low overpotential of 137 mV. A comprehensive kinetic analysis revealed that Ni and Fe play crucial roles in enhancing the adsorption and desorption of the reactant and product, respectively, while Co serves as the active site for intermediate formation, collectively boosting the activity of the trimetallic CoNiFePB. While the electron modulation achieved by B and P triggers the formation of active sites and avoids chloride ion oxidation. The bifunctional CoNiFePB catalyst deposited on Ni foam (NF) demonstrated excellent durability for 10,000 cycles and maintained performance for 70 h in chronoamperometric testing at a high current density of 0.7 A/cm2, emphasizing its long-term stability in alkaline seawater. When integrated into an advanced seawater electrolyzer with a zero-gap assembly, CoNiFePB/NF achieved a current density of 2 A/cm2 at a cell voltage of approximately 2.43 V in alkaline natural seawater. These findings provide significant insights into electrocatalysis for seawater splitting with promising implications for commercial applications. 2025 Elsevier B.V. -
Fabrication of cobalt oxide@cellulose/nitrogen doped carbon nanotubes decorated metal organic frameworks composite for symmetric supercapacitor applications
The two main issues facing the world's population now are energy storage needs and environmental protection. A lot of work has gone into creating electrochemical energy storage using chemical processes and a variety of possible electrode active materials. Supercapacitors, which are energy storage devices with a unique structure and morphology of cellulose materials for green energy resource. In this regard, solid state hydrothermal process is used to fabricate Co3O4@Cellulose (CE), Co3O4@CE/N-MWCNT, and Co3O4@CE/N-MWCNT/ZIF-67 composite materials. XRD, XPS, BET, and HR-TEM analyses verified the structural, surface, and morphological analysis. The electrochemical studies by a three- and two-electrode fabrication in presence of 1M KOH electrolyte for supercapacitor applications. When 1M KOH electrolyte is present, the fabricated Co3O4@CE/N-MWCNT/ZIF-67composite electrode displayed exceptional cyclic stability and a specific capacitance of ?835 F g?1 at 1 A/g. The constructed composite electrodes of Co3O4, Co3O4@CE, and Co3O4@CE/N-MWCNT have specific capacitances of 263, 406, and 576 F g?1 at 1 A/g, respectively, which improves electrochemical properties using a three-electrode design. The Co3O4@CE-N-MWCNT/ZIF-67//1MKOH/SSC composite is produced using two electrode configurations. The final material showed a capacitance of 258 F g?1 at 1 A/g, a capacitance retention of 84.95 % across 8000 cycles, and an energy density of 30.99 W h kg?1 at a power density of 5409 W kg?1. Hence, the composite electrodes that have been produced have the potential to be used in electrochemical systems. 2025 Elsevier B.V. -
Insights into the synergistic effect of V3S4 decorated Ti3C2 MXene as an electrode for asymmetric supercapacitor
As the globe moves toward sustainable energy options, effectively storing and managing energy becomes increasingly crucial. Advanced energy storage technologies can bridge the gap between energy generation and consumption, ensuring a reliable and stable supply even when renewable sources are intermittent. In this context, the rise of two-dimensional layered Ti3C2 MXene as a promising electrode for supercapacitors is particularly noteworthy, owing to its unique physical, chemical, and electrocatalytic attributes. Despite its potential, the immediate collapse and aggregation of MXene layers pose significant obstacles to their widespread usage in energy storage applications. This study explores advanced energy storage technologies using V3S4 coupled Ti3C2 MXene as electrodes in asymmetric supercapacitors. By combining the unique properties of V3S4 and Ti3C2 MXene, new avenues for improving the performance of supercapacitors are being unlocked. The experimental results indicate that the Ti3C2/V3S4 electrode exhibits an enhanced specific capacitance (Csp) of 1323.7 Fg-1 at a current density of 1 Ag-1, with an outstanding capacitance retention of 90.5 % after 2000 cycles. An assembled asymmetric supercapacitor, Ti3C2/V3S4//activated carbon shows superior energy storage efficiency, achieving a Csp of 258.4 Fg-1 at 2 Ag-1. The device exhibits a high energy density of 60.6 Whkg?1 at a power density of 649.2 Wkg-1, while holding onto a capacitance retention rate of 91.1 % over 10,000 cycles. 2025 Elsevier Ltd -
Facile green synthesis of MoO2/BiOCl nanocomposite using Hibiscus rosa-sinensis leaf extract and its application in visible-light-driven oxidative transformations
This article describes a green approach for synthesizing MoO2/BiOCl nanocomposite using a combustion procedure with Hibiscus rosa-sinensis leaf extract as a renewable fuel source, which also acts as a reducing and stabilizing agent. The synthesized material is characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR), confirming the successful formation of the nanocomposite. The photocatalytic performance of MoO2/BiOCl nanocomposite was evaluated for visible-light-driven oxidative transformations of different aromatic amines to nitroarenes. The unique structure of MoO?/BiOCl provides better accessibility to the reactant molecules, facilitating faster and more efficient oxidation. The advantages of this oxidative process are high catalytic efficiency, mild reaction conditions, recyclability, environmental sustainability, and producing nitroarenes in good to exceptional yields (6795 %). The conversion of the compounds was validated using gas chromatography-mass spectrometry (GCMS), 1H NMR, and 13C NMR. The results demonstrated that the MoO2/BiOCl nanocomposite exhibited enhanced photocatalytic activity compared to its components, attributed to the synergistic effects between MoO2 and BiOCl. The use of Hibiscus rosa-sinensis leaf extract in the synthesis is not only environmentally friendly and cost-effective but also contributes to the stability and efficiency of the nanocomposite. 2025 Elsevier B.V. -
Catalytic potential of fluorescein under visible light irradiation: Enabling single-pot open flask synthesis of novel pyrazolyl methanesulfonamides
This groundbreaking study introduces a novel and efficient method for synthesizing a range of substituted pyrazolyl methanesulfonamides through a five-component cyclocondensation reaction. This reaction incorporates five different components, such as ethyl acetoacetate, hydrazine, dimedone, benzaldehydes, substituted phenyl acetonitriles, and methyl sulfonyl chloride was made to react under visible light irradiation, with fluorescein serving as an effective catalyst and ethanol as solvent for 30 mintues. This method offers significant advantages, including simplified handling, higher yields of target products with shorter reaction times, and easier purification processes. We successfully synthesized around 15 novel pyrazolyl methanesulfonamide derivatives with high efficiency. Comprehensive spectral characterization confirmed the structural integrity and purity of these derivatives, demonstrating the robustness and versatility of this approach. Facilitated by visible light and utilizing fluorescein as a bio-friendly catalyst, this methodology is both green and sustainable. This innovative approach not only streamlines the synthesis of pyrazolyl methanesulfonamides but also holds considerable promise for advancing research and applications in fields such as medicinal chemistry and materials science. 2024 The Author(s) -
One-pot sustainable synthesis of novel pyrido[2,3-d]pyrimidinones and their evaluation for antitubercular and anticancer activity
A novel green protocol for the construction of diversified pyrido[2,3-d]pyrimidinones was accomplished by a single-pot reaction of aryl aldehydes, Meldrum's acid, thiobarbituric acid, and ammonium acetate/aniline in H2O using ?-proline as an expeditious reusable catalyst at room temperature (26 C). Our strategy provides an innovative synthetic avenue for the construction of pyrido[2,3-d]pyrimidinones, as well as several advantages over traditional methods, including a simple procedure, shorter reaction duration, excellent yields, safe handling, easy workup, catalyst recovery, and environmental compatibility. Furthermore, the synthesised compounds were tested for their impact on different cell lines and microorganisms. Compounds 5d and 5e were particularly effective against Mycobacterium tuberculosis (antitubercular), human breast cancer cells (MCF-7), lung cancer cells (A549 and NCI-H460), and both Gram-positive (S. pyogenes) and Gram-negative (E. coli) bacteria. The derivatives with hydroxyl and nitro substitutions [5e, 5f] showed the highest potency against MCF-7, A549, and NCI-H460 cell lines, with IC50 values of 3.684.36, 3.823.41, and 11.3412.28 g/mL, respectively. 2024 The Author(s) -
Process optimization of SLA-fabricated BN-reinforced photopolymer composites using ANOVA for improved tensile strength
This study examined how the mechanical characteristics of 3D-printed photopolymer composites are affected by the inclusion of boron nitride (BN). Stereolithography technology was used to print BN-reinforced photosensitive resin composites with different BN weight percentages (0, 0.5, 1.0, and 1.5 wt%). The effect of process parameters - Material composition, build angle, post-curing time, and lift speed) on the tensile strength of the printed specimens were evaluated using a Taguchi L16 orthogonal array. The microstructure and elemental composition of the composites were characterized using energy-dispersive X-ray spectroscopy (EDAX) and scanning electron microscopy (SEM). Tensile tests were performed in accordance with ASTM D638 Type IV, and the findings were assessed using an analysis of variance (ANOVA) and signal-to-noise (S/N) ratio. SEM and EDAX investigations revealed that BN was evenly distributed throughout the photosensitive resin matrix. The ANOVA results showed that post-curing time had the biggest effect on tensile strength (38.283 % contribution), followed by material composition (27.669 %), lift speed (16.265 %), and build angle (17.782 %). For the maximum tensile strength, the ideal set of process parameters was determined to be 1.5 wt percent BN, 90 build angle, 60 min post-curing time, and 60 mm per minute lift speed. Significant interactions between the parameters under study were displayed by interaction plots. This study offers important insights into optimizing SLA process settings for increased tensile strength and shows how BN-reinforced photopolymer composites can improve the mechanical properties of SLA-printed objects. Copyright 2025. Published by Elsevier B.V. -
On the fully compensated ferrimagnetism in Mn2V1-xCoxAl (x=0, 0.25, 0.5, 0.75, 1) Heusler alloys: An ab initio and neutron diffraction study
We present a detailed ab initio investigation on the interesting Heusler alloys Mn2V1-xCoxAl (x=0,0.25,0.5,0.75,1), which exhibit fully compensated ferrimagnetism with high Curie temperature for x = 0.5. Calculations were performed by incorporating various atomic anti-site disorders, and the minimum energy structure causing the fully compensated ferrimagnetic state with high Curie temperature in Mn2V0.5Co0.5Al was identified to be L 21 with Mn-Co disorder. This L 21 phase, along with the ferrimagnetic interaction among the parallelly coupled (Mn(A)-Mn(C)) and (V-Co) pairs, gives rise to the fully compensated ferrimagnetism in the half-metallic Mn2V0.5Co0.5Al Heusler alloy. Increasing Co concentration in Mn?VAl induces a change in structure from the L 2? phase to the X ? phase. The peculiar spin gapless semiconducting behavior of Mn2CoAl was evident from the ab initio results. Ab initio results have explained the previously reported anomalies in the electrical resistivity of Mn2V1-xCoxAl. Neutron diffraction analysis has confirmed, for the first time, that Mn2V0.5Co0.5Al has a disordered L 2? structure, which agrees with the ab initio results. 2025 Elsevier B.V. -
Electrical transport and magnetoresistance studies on the magnetic moment compensated Mn2V1-xCoxZ (Z=Ga, Al; x=0, 0.25, 0.5, 0.75, 1) Heusler alloys
We report the electrical resistivity and magnetoresistance properties of arc-melted Mn2V1-xCoxZ (Z=Ga, Al; x =0, 0.25, 0.5, 0.75, 1) alloys, which possess compensated ferrimagnetic behaviour with high TC when x=0.5. Apart from metallicity, the alloys in the Ga series with x= 0, 0.75, 1 composition showed a positive to negative crossover in the magnetoresistance versus temperature curves. This crossover was absent for Mn2V0.75Co0.25Ga and the fully compensated ferrimagnet Mn2V0.5Co0.5Ga. In contrast to this, Co-substituted Mn2VAl exhibits distinctly different resistive behaviour. While the alloys Mn2VAl and Mn2CoAl exhibit metallic and semiconducting behaviour respectively, the intermediate compositions show a gradual metallic to semiconducting transition as the Co concentration increases. The compensated ferrimagnet Mn2V0.5Co0.5Al showed a mixed transport behaviour of metallic and semiconducting nature with a resistivity minimum at 140 K. In contrast to this mixed response of the arc-melted bulk sample, the Mn2V0.5Co0.5Al melt-spun ribbon shows a clear semiconducting nature throughout the temperature range, indicating that the sample preparation methods could highly influence the electrical properties of the investigated compensated ferrimagnets. 2024 Elsevier B.V. -
DFT study of structural and electronic properties of [Fe(CO)4(PbX)] complexes (X = O, S, Se and Te): Influence of terminal lead chalcogenide ligands on bonding and stability
Density Functional Theory (DFT) calculations at the B3LYP level were performed to investigate the structural and electronic properties of axial and equatorial isomers of [Fe(CO)4(PbX)] complexes, where X = O, S, Se, and Te. Total energy evaluations indicate that equatorial isomers are generally more stable than their axial counterparts. Detailed bonding analysis was carried out using Natural Population Analysis (NPA) and Energy Decomposition Analysis (EDA), providing insight into the nature of the FePbX interactions. The FePbX bond strengths were further assessed through Wiberg Bond Index (WBI) calculations. Frontier Molecular Orbital (FMO) analysis revealed HOMOLUMO gaps ranging from 3.04 to 3.97 eV, all of which are narrower than the corresponding gap in Fe(CO)5, suggesting enhanced electronic reactivity due to PbX substitution. Natural Bond Orbital (NBO) analysis indicated a greater electron density contribution from the Pb atom to the FePb bond, whereas for FeC bonds, carbon atoms contributed more significantly than Pb. These results collectively highlight the influence of terminal lead chalcogenide ligands on both the geometric and electronic structure of iron carbonyl complexes. 2025 Elsevier Inc. -
Multi-variate LSTM with attention mechanism for the Indian stock market
The advent of attention mechanism has surpassed numerous benchmarks and enabled widespread progress in the realm of natural language processing (NLP). Nevertheless, they have not been adequately leveraged in a time-series context. Accordingly, this paper aims to address this issue by proposing a hybrid, deep-learning model that integrates attention mechanisms and multi-variate long short-term memory (LSTM) for financial forecasting in the Indian stock market. Our model yields superior results as compared to baseline and state-of-the-art models evaluated using MAE and RMSE. Moreover, we employed a modern evaluation criterion based on the methodology advocated by DieboldMariano, known as the DieboldMariano test (DM test), as a new criterion for evaluation based on statistical hypothesis tests. DM test has been applied in this study to distinguish the significant differences in forecasting accuracy between LSTM with attention and other models. From the results and according to DM-test it is observed that the differences between the forecasting performances of models are significant and that attention mechanism could enhance the accuracy in predicting stock prices by allowing the model to prioritize and concentrate on the most important features and patterns in the data while avoiding overfitting and noise. 2025 The Author(s) -
Polyaniline/zinc oxide nanocomposites for Dye-sensitized solar cell device fabrication and analysis
Zinc oxide nanoparticles synthesized by hydrothermal technique are used as reinforcements to synthesize polyaniline nanocomposite via in-situ chemical oxidation method. The XRD analysis confirms the formation of polyaniline/zinc oxide nanocomposites. SEM images shows that nano reinforcement is covered with polymer matrix. Nanoparticles are found to be immersed in polyaniline matrix in the TEM images of nanocomposites. Significance of filler morphology in polyaniline nanocomposites is analysed by reinforcing zinc oxide nanoflowers, rods and spheres into polyaniline. Addition of metal oxide into polyaniline improves thermal stability. An increase of 227 % in UV absorption is observed for nanoflower composite compared to pure polyaniline in the absorption spectrum. Photoluminescence spectral analysis shows minimum peak intensity for polyaniline/zinc oxide nanoflower composite. Based on the optical property analysis, Dye-sensitized solar cells are fabricated by coating polyaniline and its nanocomposite with zinc oxide nanoflower. Power conversion efficiency of 5.23 % is obtained for the device based on pristine polyaniline and 7.03 % for nanoflower composite. 2026 Indian Chemical Society. -
Development and characterization of Fe2O3 nanoparticles coated with chitosan and folic acid for biomedical applications
Polymeric inorganic nanoparticles have emerged as promising nanomedicines due to their unique properties, offering enhanced antibacterial and anticancer effects. Thus, the study focus on the synthesis of Fe2O3 and Fe2O3 coated with chitosan and folic acid nanoparticles (Fe2O3-CS-FA NPs) mediated by Tagetes erecta (T. erecta) extract and assess their biological effects. The synthesized NPs are analysed by various characterisation techniques. FTIR spectroscopy of Fe2O3 and Fe2O3 -CS-FA NPs revealed characteristic peaks corresponding to Fe2O3, chitosan, and folic acid molecules. The XRD pattern confirmed the successful synthesis of Fe2O3 NPs and Fe2O3 -CS-FA NPs, indicating a rhombohedral structure. FESEM demonstrated spherical structures for both Fe2O3 and Fe2O3 -CS-FA NPs. Antimicrobial activity was assessed against various pathogens using the disk diffusion method, showing that Fe2O3-CS-FA NPs demonstrated superior antibacterial activity compared to Fe2O3 NPs. In terms of antioxidant activity, Fe2O3 -CS-FA NPs showed the highest scavenging activity against DPPH, outperforming Fe2O3 NPs. The anticancer activity of both Fe2O3 NPs and Fe2O3 -CS-FA NPs was tested against the HCT-116 human colon cancer cell line, where Fe2O3 -CS-FA NPs demonstrated greater anticancer activity with an IC50 value of 10.2 ?g/mL compared to Fe2O3 at 13.8 ?g/mL. Based on the findings of this research, there is a strong indication that Fe2O3 -CS-FA NPs hold significant potential as a nanomaterial well-suited for advanced biomedical applications in the industry. 2025 Indian Chemical Society -
Surface modified CaO nanoparticles with CMC/D-carvone for enhanced anticancer, antimicrobial and antioxidant activities
The rising prevalence of antimicrobial resistance and the continued challenge to cancer therapy are in desperate need of developing innovative therapeutic strategies. In this regard, the present research work focuses on the development of CaO NPs and CaO-CMC-Dcar nanocomposites for enhanced antimicrobial and anti-cancer activities. CaO nanoparticles were synthesized by facile one pot chemical approach and eventually functionalized with CMC and D-carvone biomolecules. XRD analysis revealed that the crystallite size for CaO and CaO-CMC-Dcar nanoparticles was found to be 21.18 nm and 17.02 nm respectively. The band gap values obtained for CaO and CaO-CMC-Dcar nanoparticles were 4.44 eV, and 4.25 eV respectively. The CaO-CMC-Dcar nanoparticles show absorption maxima at 292 nm, slightly red-shifted from bare CaO nanoparticles. HRTEM and SEM analysis revealed that the prepared samples were roughly spherical and agglomerated in nature. Antimicrobial activity was evaluated against methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans. The zone of inhibition (ZOI) for CaO-CMC-Dcar nanoparticles against MRSA and C. albicans was 20.1 0.3 mm and 21.1 0.2 mm, respectively, significantly higher than that of pure CaO nanoparticles (14.1 0.2 mm and 13.2 0.1 mm) and comparable to standard anti-bacterial streptomycin and antifungal fluconazole discs. Anticancer activity was assessed via MTT assay against MOLT-4 blood cancer cells, where the IC50 values for CaO and CaO-CMC-Dcar nanoparticles were 22.6 ?g/mL and 21.54 ?g/mL, respectively. Additionally, CaO-CMC-Dcar nanoparticles exhibited enhanced antioxidant activity (80 %) compared to CaO (70 %) at 20 ?g/mL, with performance comparable to that of Vitamin C. Experimental results revealed that the CaO-CMC-Dcar nanoparticles exhibited superior biological activity compared to pure CaO nanoparticles. 2025 Indian Chemical Society -
New constraints on f(T) gravity from DESI DR2 and dark energy survey supernovae
We present new observational constraints on three viable f (T) gravity parametrizationsthe Power Law (f 1CDM), Linder (f 2CDM), and Exponential (f 3CDM) modelsusing the latest Baryon Acoustic Oscillations (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2). We combine the spectroscopic DESI-DR2 data with Cosmic Chronometer (CC) measurements, the Type Ia Supernovae sample from the Dark Energy Survey (DES) Year 5, and early-universe CMB distance priors to break parameter degeneracies. Our Bayesian MCMC analysis reveals that while late-time data alone suggests a statistical preference for a non-zero deviation from GR at the 1 ? 2 ? level, the inclusion of CMB priors pulls the models significantly closer to the standard ?CDM limit. Specifically, we constrain the joint dataset distortion parameters to p1=?0.002?0.041+0.047, 1/p2=0.156?0.057+0.10, and 1/p3=0.144?0.023+0.071. Across all three models, the addition of early-universe data anchors the inferred Hubble constant to sub-percent precision, clustering around H0?67.3?67.7kms?1Mpc?1, showing excellent agreement with Planck 2018 results but remaining in tension with local SH0ES calibrations. Statistical model comparison demonstrates that while late-time data favors the f (T) extensions (?AIC'?2), the comprehensive joint analysis renders them statistically indistinguishable from ?CDM based on the Akaike Information Criterion (?AIC ? 2). Furthermore, the Bayesian Information Criterion (BIC) finds moderate to strong evidence against the extensions (4 ' ?BIC ? 7.5) due to the penalty on model complexity. We conclude that while current precision data accommodate late-time torsional modifications to gravity, the standard ?CDM model remains a statistically sufficient and more parsimonious description of the cosmic expansion when considering the full evolutionary history. 2026 Elsevier B.V. -
Cosmic acceleration from topological fluctuations of quantum spacetime
The observed late-time acceleration of the Universe challenges our understanding of gravity and the quantum vacuum. We investigate the framework of Topological Dark Energy, where cosmic acceleration emerges not from a fundamental cosmological constant or exotic fields, but from the topological structure of quantum spacetime. In this picture, the vacuum is a dynamic spacetime foam in which gravitational instantons-non-perturbative configurations in Euclidean quantum gravity-nucleate and alter global topology. The cumulative effect of these processes, coupled to macroscopic gravity through the Gauss-Bonnet invariant, yields a dynamical effective cosmological constant, ?eff. Its sign and magnitude are determined by the statistical ensemble of instantons, allowing the dark energy equation of state to evolve across the phantom divide. By embedding the Topological Dark Energy in a FriedmannLemareRobertsonWalker background, we derive its background and linear perturbative cosmological dynamics and confront the model with DESI DR2 BAO, Union3 supernova, and Planck CMB data. The results show that Topological Dark Energy is observationally viable, reproducing key features of the expansion history while offering a theoretically motivated alternative to ?CDM. 2026 Elsevier B.V. -
Ultraviolet variability in radio-loud active galactic nuclei observed by UVIT onboard AstroSat
Radio-loud active galactic nuclei (AGN) are among the most luminous objects in the Universe, emitting radiation from low-energy radio waves to high energy ? -rays. They are well known to exhibit flux variations at nearly all accessible wavelengths. However, their variability properties in the ultraviolet (UV) band remain relatively less explored compared to other wavebands. Here, we present the results of a systematic investigation of the UV flux and spectral variability characteristics of 24 radio-loud AGN spanning the redshift range 0.018 ? z ? 2.218. The sample comprises 17 BL Lac objects, 6 flat spectrum radio quasars (FSRQs) and one radio-loud narrow line Seyfert 1 galaxy. We used observations obtained with the Ultra-Violet Imaging Telescope (UVIT) onboard AstroSat during its first ten years of operation, covering both the far-UV (FUV; 1300 - 1800 and near-UV (NUV; 2000 - 3000 bands. Of the 24 sources analysed, 18 showed significant UV variability on hour timescales. We found a bluer when brighter (BWB) spectral trend in two sources: the FSRQ CTA 102 and the BL Lac PKS 0447 - 439. The observed UV variability in our sample of radio-loud AGN, together with the BWB trend detected in these two sources, supports a scenario in which the hour timescale UV variations are driven by intrinsic processes within their relativistic jets. 2026 Elsevier B.V. -
The indian pulsar timing array data release 2: II. Customised single-pulsar noise analysis and noise budget
We present the results of customised single-pulsar noise analysis of 27 millisecond pulsars from the second data release of the Indian Pulsar Timing Array (InPTA-DR2). We model various stochastic noise sources present in the dataset using stationary Gaussian processes and estimate the noise budget of the InPTA-DR2 using Bayesian inference, involving model selection, Fourier harmonics selection, and parameter estimation for each pulsar. We check the efficacy of our noise characterisation by performing the Anderson-Darling test for Gaussianity on the noise-subtracted residuals. We find that all 11 pulsars with time baseline ? 2.5 yr show Gaussian residuals and do not have evidence for any red noise process in the optimal model, except for PSR J1944 + 0907, which shows presence of DM noise. PSRs J0437 - 4715, J1909 - 3744 and J1939 + 2134 show preference for the most complicated noise model, having achromatic and chromatic red noise processes. Only 4 out of 15 pulsars with time baseline ? 2.5 yr show significant non-Gaussianity in noise-subtracted residuals. We suspect that this may require more advanced methods to model noise processes properly. A comparative study of six pulsars with data removed near solar conjunctions showed deviations from the parameter estimates obtained with the original dataset, indicating potential bias in red noise processes due to unmodeled solar-wind effects. The results presented in this work remain broadly consistent with the InPTA-DR1 noise budget, with better constraints obtained on noise processes for several pulsars and support for achromatic red noise in PSR J1012 + 5307 due to the extended time baseline. 2026 The Author(s). -
Detection of time delay between UV and X-ray variability in Mrk 1044 using AstroSat observations
Active galactic nuclei are known to exhibit flux variations across the entire electromagnetic spectrum. Among these, correlations between UV/optical and X-ray flux variations serve as a key diagnostics for understanding the physical connection between the accretion disk and the corona. In this work, we present the results of analysis of ultraviolet (UV) and X-ray flux variations in the narrow line Seyfert 1 galaxy Mrk 1044. Simultaneous observations in the far-UV band (FUV: 1300 - 1800 and the X-ray band (0.5 - 7 keV) obtained during 31 August - 8 September 2018 with the Ultraviolet Imaging Telescope and the Soft X-ray Telescope onboard AstroSat were used for this study. Significant flux variability was detected in both FUV and X-ray bands. The fractional root mean square variability amplitude ( F var) was found to be 0.036 0.001 in the FUV band and 0.384 0.004 in the X-ray band. To explore potential time lag between the two bands, cross-correlation analysis was performed using both the interpolated cross-correlation function (ICCF) and just another vehicle for estimating lags in nuclei (JAVELIN) methods. Results from both approaches are consistent within 2 ? uncertainty, indicating that X-ray variations lead the FUV variations, with measured lags of 2.25 0.05 days (ICCF) and 2.35?0.01+0.02 days (JAVELIN). This is the first detection of a time delay between UV and X-ray variations in Mrk 1044. The observed UV lag supports the disk reprocessing scenario, wherein X-ray emission from the corona irradiates the accretion disk, driving the observed UV variability. 2026 Elsevier B.V. -
Effects of coronal mass ejection on PSR J1022+1001 and possible mode change of PSR J2145 - 0750 in the InPTA DR2
The Indian Pulsar Timing Array (InPTA) has recently published its second data release (DR2), comprising the timing analysis of seven years of data on 27 millisecond pulsars (MSPs), observed simultaneously in the 300 - 500 MHz (band 3) and 1260 - 1460 MHz (band 5), using the upgraded Giant Metrewave Radio Telescope (uGMRT). The low-frequency data, particularly in band 3, is highly sensitive to propagation effects such as dispersion measure (DM) fluctuations, which can be imprints of some astrophysical phenomena (scientific outliers). Here, we analyze the two outliers of possible astrophysical origin coming from the band 3 DM time series of two pulsars: PSR J1022+1001, with an ecliptic latitude of ?0.06?, and PSR J2145 - 0750, one of the brightest MSPs, with multi-component profile morphology. Our study reveals compelling evidence for a coronal mass ejection (CME) event traced in the data of PSR J1022+1001, and reports evidence for a potential mode-changing event in PSR J2145 - 0750. By contrasting these two cases, we show that DM fluctuations due to CME interacions and intrinsic mode-changing events produce distinct observational signatures, enabling a physically informed classification of scientific outliers in PTA datasets. Extending the analyses presented here to the full sample of InPTA-DR2 pulsars is expected to reveal additional CME events, and possible mode-changing events. Such detections will not only improve our understanding of solar and pulsar magnetospheric plasma interactions but will also enable more accurate modelling of DM variations, leading to improved pulsar timing solutions, which are crucial for high-precision Pulsar Timing Array (PTA) science. 2026 Elsevier B.V.