Browsing by Author "Archana Gupta"

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Active, passive and transpassive dissolution of In-718 alloy in acidic solutions
(2004) V.B. Singh; Archana Gupta
The electrochemical behaviour of In-718 alloy in different compositions of binary and ternary solution mixtures of concentrated phosphoric, sulphuric, acetic acids and in different concentrations of aqueous and methanolic solutions of sulphuric acid has been studied by potentiostatic polarisation technique at 30°C. The cathodic polarisation curves are almost linear and similar in all the solution mixtures and cathodic reaction is hydrogen evolution. The anodic polarisation curves reveal active, passive and transpassive behaviour in all the solution mixtures. In the transpassive region, a current plateau was observed in most of the cases in binary and ternary solution mixtures but electropolishing was not observed in any case. The results show that the existence of a current plateau is not the only sufficient condition for achieving electropolishing of the alloy. © 2003 Published by Elsevier B.V.
Deep learning-based segmentation of gallbladder cancer on abdominal computed tomography scans: a multicenter study
(Springer, 2025) Pankaj Kumar Gupta; Niharika Dutta; Ajay Tomar; Shravya Singh; Sonam Choudhary; Nandita Mehta; Vansha Mehta; Rishabh Sheth; Divyashree Srivastava; Salai Thanihai; Palki Singla; Gaurav Prakash; Thakur Deen Yadav; Lileswar Kaman; Santhosh Irrinki; Harjeet Singh; Niket Shah; Amit Kumar J. Choudhari; Shraddha Patkar; Mahesh Goel; Rajanikant R. Yadav; Archana Gupta; Ishan Kumar; Kajal Seth; Usha K. Dutta; Chetan P. Arora
Objectives: To train and validate segmentation models for automated segmentation of gallbladder cancer (GBC) lesions from contrast-enhanced CT images. Materials and methods: This retrospective study comprised consecutive patients with pathologically proven treatment naïve GBC who underwent a contrast-enhanced CT scan at four different tertiary care referral hospitals. The training and validation cohort comprised CT scans of 317 patients (center 1). The internal test cohort comprised a temporally independent cohort (n = 29) from center 1 (internal test 1). The external test cohort comprised CT scans from three centers [(n = 85)]. We trained the state-of-the-art 2D and 3D image segmentation models, SAM Adapter, MedSAM, 3D TransUNet, SAM-Med3D, and 3D-nnU-Net, for automated segmentation of the GBC. The models’ performance for GBC segmentation on the test datasets was assessed via dice score and intersection over union (IoU) using manual segmentation as the reference standard. Results: The 2D models performed better than 3D models. Overall, MedSAM achieved the highest dice and IoU scores on both the internal [mean dice (SD) 0.776 (0.106) and mean IoU 0.653 (0.133)] and external [mean dice (SD) 0.763 (0.098) and mean IoU 0.637 (0.116)] test sets. Among the 3D models, TransUNet showed the best segmentation performance with mean dice (SD) and IoU (SD) of 0.479 (0.268) and 0.356 (0.235) in the internal test and 0.409 (0.339) and 0.317 (0.283) in the external test sets. The segmentation performance was not associated with GBC morphology. There was weak correlation between the dice/IoU and the size of the GBC lesions for any segmentation model. Conclusion: We trained 2D and 3D GBC segmentation models on a large dataset and validated these models on external datasets. MedSAM, a 2D prompt-based foundational model, achieved the best segmentation performance. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.
Direct and residual effect of sewage sludge on yield, heavy metals content and soil fertility under rice-wheat system
(Elsevier, 2014) A.M. Latare; Omkar Kumar; S.K. Singh; Archana Gupta
Soil application of sewage sludge in crop production offers an alternative technique for its disposal and management. The present study was taken up to evaluate the effect of sewage sludge on yield of rice, soil fertility and heavy metals accumulation in grain and straw in a glass house. The residual effect of sludge application was evaluated in subsequent wheat crop in the sequence. Five doses of sludge i.e., 0, 10, 20, 30 and 40tha-1 were applied to rice and their effects were compared with the recommended dose of fertilizers i.e., 120, 60 and 60kgN, P2O5 and K2Oha-1, respectively. There was significant increase in straw and grain yields of both the crops with application of sludge. The grain yield of rice increased 45% at 40tha-1 sludge application over no sludge. The residual effect on wheat yield was more pronounced. Soil pH in post harvest rice soil increased with the application of sludge, however, it decreased in post harvest wheat soil at higher levels of sludge application. Increase in available nutrients content of soil was also recorded with increasing levels of sludge application after harvest of rice and wheat crops. Application of sludge also increased the heavy metals contents in soil and plant. The Cd content in rice grain was above the Indian safe limit at 20tha-1 or higher levels of sludge application. There was a significant build up of P, S, Zn, Fe, and Mn in post harvest wheat soil at 40tha-1 sludge application. © 2014 Elsevier B.V.
Dissolution and inhibition of Monel (400) alloy in aqueous formic and acetic acid solutions
(2001) B.V. Singh; R.N. Singh; Archana Gupta
The corrosion behaviour of Monel (400) in different concentrations of formic and acetic acid solutions has been studied by potentiostatic technique, at different temperatures (30, 37 and 44°C). The maximum corrosion is observed in aqueous 20 mol/O formic and acetic acid solution. It was found that the extent of corrosion of the alloy is a function of acid concentration. The anodic polarisation curves show active corrosion behaviour of the alloy over the whole range of potential at each concentration of both the acids, individually. The cathodic polarisation curves are almost identical irrespective of the concentration of either acid. The inhibitive effect of some organotin compounds viz. Bu2SnCl2, PhSnCl3, Ph2SnCl2 and Ph3SnCl on the corrosion of monel (400) has been studied in aqueous solution mixture (20 mol/O) of either acid. The results have been discussed in the light of molecular structures of the organotin compound and their adsorption on the surface of the corroding metal. Among the inhibitors used Ph3SnCl functions as a better inhibitor in both the acids. SEM studies also show that the inhibitors act as passivator type inhibitor in acetic acid.
Microstructural and corrosion studies of 9Cr-1Mo steel in acidic methanol solutions
(2005) V.B. Singh; Archana Gupta
The corrosion behaviour of 9Cr-1Mo ferritic steel has been studied in methanol containing different concentrations of sulphuric, hydrochloric acids and their mixtures using potentiostatic and potentiodynamic techniques at 30°C. The influence of various heat treatments: furnace cooled (FC), air cooled (AC) and water quenched (WQ) on the electrochemical polarization behaviour has also been studied for a few selected compositions of these acids and their mixtures in methanolic solutions. The cathodic reaction is observed to be hydrogen evolution. The alloy showed active, passive and transpassive behaviour in different concentrations of sulphuric acid in methanol. The anodic polarization curves of the alloy revealed a characteristic 'cathodic loop' in methanol at higher concentrations of sulphuric acid (0.1 and 1.0 M). Stable passivity was also observed which became ustable at higher potential due to pitting. Well defined anodic Tafel region followed by a limiting current density region, in different concentrations of methanolic solution of hydrochloric acid, was observed. However, in the mixture of different concentrations of sulphuric acid and hydrochloric acids in methanol and at higher concentration of sulphuric acid (1.0 M) the alloy showed active, passive and transpassive behaviour. Such behaviour was not observed below 1.0 M concentration of either acid in methanol, rather a limiting nature was observed. It seems that in the acidic mixture, the SO2-4 ions act as inhibitor and decreases the adsorption of Cl- ions and at sufficiently high concentration it effectively hinders the adsorption of the Cl- ions on the surface. The anodic polarization curves for FC specimen shifted towards higher current density region and the curves for AC and WQ specimens shifted towards lower current density region in comparison to as-received one in methanolic solution of sulphuric acid. However, the anodic polarization curves for FC, AC and WQ specimen shifted towards higher current density region as compared to as-received specimen in methanolic solution of hydrochloric acid and in the mixture of hydrochloric and sulphuric acids in methanol. Examination of the sample surface was done using scanning electron microscopy (SEM).
Ventriculo-peritoneal shunts can cause liver injury, juxta and intrahepatic pseudocysts: Imaging findings and review of literature
(2012) Ashish Verma; Suyash Mohan; Archana Gupta
[No abstract available]