Browsing by Author "Ashish Kumar"

Now showing 1 - 20 of 104

2-Dimensional Magnesium Oxide/Polyaniline Nanocomposite Modified Glassy Carbon Electrode for Electrochemical Detection of Dopamine and 4-Nitrophenol
(John Wiley and Sons Inc, 2024) Ashish Kumar; Surbhi Sharma; Chandra Shekhar Pati Tripathi; Debanjan Guin
In this study, we have developed an electrochemical sensor based on a polyaniline (PANI) integrated magnesium oxide nanosheet (MgO-NSs) modified glassy carbon electrode (GCE) for the rapid electrochemical detection of dopamine (DA) and 4-nitrophenol (4-NP). 2-D MgO-NSs were synthesized using a straightforward one-step sugar-blowing method, and PANI was synthesized by the oxidative polymerization of aniline. The nanocomposite (PANI-MgO) was prepared by simple mechanical blending of MgO-NSs with PANI. The as-synthesized nanocomposites were characterized using several analytical techniques to determine their morphological and microstructural properties. The as-synthesized PANI, MgO, and PANI-MgO were further electrochemically characterized using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) techniques. The fabricated PANI-MgO/GCE showed a considerable increase in the redox peak currents of DA and 4-NP, suggesting that PANI-MgO/GCE substantially enhances the electrocatalytic oxidation of DA and the reduction of 4-NP. The analytical performance of PANI-MgO/GCE for the detection of DA and 4-NP was investigated using Differential Pulse Voltammetry (DPV). The developed sensor was successfully applied for the detection of DA and 4-NP in real samples with good recovery results. © 2024 Wiley-VCH GmbH.
2019 Update of Indian National Association for Study of the Liver Consensus on Prevention, Diagnosis, and Management of Hepatocellular Carcinoma in India: The Puri II Recommendations
(Elsevier B.V., 2020) Ashish Kumar; Subrat K. Acharya; Shivaram P. Singh; Anil Arora; Radha K. Dhiman; Rakesh Aggarwal; Anil C. Anand; Prashant Bhangui; Yogesh K. Chawla; Siddhartha Datta Gupta; Vinod K. Dixit; Ajay Duseja; Naveen Kalra; Premashish Kar; Suyash S. Kulkarni; Rakesh Kumar; Manoj Kumar; Ram Madhavan; V.G. Mohan Prasad; Amar Mukund; Aabha Nagral; Dipanjan Panda; Shashi B. Paul; Padaki N. Rao; Mohamed Rela; Manoj K. Sahu; Vivek A. Saraswat; Samir R. Shah; Shalimar; Praveen Sharma; Sunil Taneja; Manav Wadhawan
Hepatocellular carcinoma (HCC) is one of the major causes of morbidity, mortality, and healthcare expenditure in patients with chronic liver disease in India. The Indian National Association for Study of the Liver (INASL) had published its first guidelines on diagnosis and management of HCC (The Puri Recommendations) in 2014, and these guidelines were very well received by the healthcare community involved in diagnosis and management of HCC in India and neighboring countries. However, since 2014, many new developments have taken place in the field of HCC diagnosis and management, hence INASL endeavored to update its 2014 consensus guidelines. A new Task Force on HCC was constituted that reviewed the previous guidelines as well as the recent developments in various aspects of HCC that needed to be incorporated in the new guidelines. A 2-day round table discussion was held on 5th and 6th May 2018 at Puri, Odisha, to discuss, debate, and finalize the revised consensus statements. Each statement of the guideline was graded according to the Grading of Recommendations Assessment Development and Evaluation system with minor modifications. We present here the 2019 Update of INASL Consensus on Prevention, Diagnosis, and Management of Hepatocellular Carcinoma in India: The Puri-2 Recommendations. © 2019
A fluorescent Ce-EDTA probe for the sensing of ascorbic acid and lysine in real samples
(Royal Society of Chemistry, 2022) None Rajpal; Ashish Kumar; Subhajit Jana; Priya Singh; Rajiv Prakash
In the present work, a fluorescent probe based on an aqueous dispersion of coordination complex Ce-EDTA is utilized for sensing carboxyl compounds. Ce-EDTA is synthesized herein by a hydrothermal method with the help of stoichiometric ratios of cerium (Ce) (+iii) salts and green ligand ethylenediamine N,N,N,N tetra-acetic acid (EDTA). In Ce-EDTA, the Ce ion is surrounded by hexadentate EDTA and three labile aqua ligands, evidenced by FT-IR, XPS, and UV-visible spectroscopy. It exists in the form of polygonal microplates, as apparent by SEM. The sensing mechanism is proposed by choosing carboxyl groups as a part of the ring and open chain. Under the optimized situations, the fluorescence intensities of Ce-EDTA are monitored towards various concentrations of l-lysine (Lys) and ascorbic acid (AA) in these regards. They exhibit a linear response from 20.29 μM to 251.74 μM and 5.62 μM to 60.87 μM with a linear correlation coefficient (R2) of 0.98 and 0.99, respectively. The lower limit of detection is observed as 3.6 μM in the case of Lys and 2.04 μM in the case of AA. The as-prepared probe exhibits suitability for selectivity of AA and Lys in the presence of various interfering agents as well as in real samples for the detection of AA in orange and Lys in soybean seed. © 2022 RSC.
A phase II, non-comparative randomised trial of two treatments involving liposomal amphotericin B and miltefosine for post-kala-azar dermal leishmaniasis in India and Bangladesh
(Public Library of Science, 2024) Shyam Sundar; Krishna Pandey; Dinesh Mondal; Major Madhukar; Roshan Kamal Topno; Ashish Kumar; Vinod Kumar; Deepak Kumar Verma; Jaya Chakravarty; Rahul Chaubey; Poonam Kumari; Md. Utba Rashid; Shomik Maruf; Prakash Ghosh; Sheeraz Raja; Joelle Rode; Margriet Den Boer; Pradeep Das; Jorge Alvar; Suman Rijal; Fabiana Alves
Background In Southeast Asia, treatment is recommended for all patients with post-kala-azar dermal leishmaniasis (PKDL). Adherence to the first-line regimen, twelve weeks of miltefosine (MF), is low and ocular toxicity has been observed with this exposure period. We assessed the safety and efficacy of two shorter-course treatments: liposomal amphotericin B (LAmB) alone and combined with MF. Methodology/Principal findings An open-label, phase II, randomized, parallel-arm, non-comparative trial was conducted in patients with parasitologically confirmed PKDL, 6 to ≤60 years. Patients were assigned to 20 mg/kg LAmB (total dose, in five injections over 15 days) alone or combined with allome-tric MF (3 weeks). The primary endpoint was definitive cure at 12 months, defined as complete resolution of papular and nodular lesions and >80% re-pigmentation of macular lesions. Definitive cure at 24 months was a secondary efficacy endpoint. 118/126 patients completed the trial. Definitive cure at 12 months was observed in 29% (18/63) patients receiving LAmB and 30% (19/63) receiving LAmB/MF (mITT), increasing to 58% and 66%, respectively, at 24 months. Most lesions had resolved/improved at 12 and 24 months for patients receiving LAmB (90%, 83%) and LAmB/MF (85%, 88%) by qualitative assessment. One death, unrelated to study drugs, was reported; no study drug-related serious adverse events were observed. The most frequent adverse drug reactions were MF-related vomiting and nausea, and LAmB-related hypokalaemia and infusion reactions. Most adverse events were mild; no ocular adverse events occurred. Conclusions/Significance Both regimens are suitably safe and efficacious alternatives to long-course MF for PKDL in South Asia. © 2024 Sundar et al.
A saponification-triggered gelation of ester-based Zn(II) complex through conformational transformations
(2014) Ashish Kumar; Mrigendra Dubey; Amit Kumar; Daya Shankar Pandey
Novel saponification-triggered gelation in an ester-based bis-salen Zn(II) complex (1) is described. Strategic structural modifications induced by NaOH in 1 tune the dipolar-/π-interactions leading to J-aggregation and the creation of an inorganic gel material (IGM>), which has been established by photophysical, DFT and rheological studies. © 2014 Partner Organisations.
A schiff base and its copper(II) complex as a highly selective chemodosimeter for mercury(II) involving preferential hydrolysis of aldimine over an ester group
(American Chemical Society, 2014) Ashish Kumar; Mrigendra Dubey; Rampal Pandey; Rakesh Kumar Gupta; Amit Kumar; Alok Ch. Kalita; Daya Shankar Pandey
The syntheses of a new Schiff base, diethyl-5-(2-hydroxybenzylidene) aminoisophthalate (HL), and a copper complex, [Cu(L2)] (1), imparting L-, have been described. Both the ligand HL and complex 1 have been thoroughly characterized by elemental analyses, electrospray ionization mass spectrometry, FT-IR, NMR (1H and 13C), electronic absorption, and emission spectral studies and their structures determined by X-ray single-crystal analyses. Distinctive chemodosimetric behavior of HL and 1 toward Hg2+ has been established by UV/vis, emission, and mass spectral studies. Comparative studies further revealed that the chemodosimetric response solely originates from selective hydrolysis of the aldimine moiety over the ester group and 1 exhibited greater selectivity toward Hg2+ relative to HL while the sensitivity order is reversed. Further, these followed different hydrolytic pathways but ended up with the same product analyzed for diethyl-5-aminoisophthalate (DEA). Hg2+-induced displacement of Cu2+ and subsequent hydrolysis of the -HC=N- moiety in 1 affirmed the identity of the actual species undergoing hydrolysis as HL. The occurrence of Cu2+ displacement and Hg2+ detection via hydrolytic transformation has been supported by various physicochemical studies. © 2014 American Chemical Society.
A serine protease KLK8 emerges as a regulator of regulators in memory: Microtubule protein dependent neuronal morphology and PKA-CREB signaling
(Nature Publishing Group, 2018) Arpita Konar; Ashish Kumar; Bryan Maloney; Debomoy K. Lahiri; Mahendra K. Thakur
The multitude of molecular pathways underlying memory impairment in neurological disorders and aging-related disorders has been a major hurdle against therapeutic targeting. Over the years, neuronal growth promoting factors, intracellular kinases, and specific transcription factors, particularly cyclic AMP response element-binding protein (CREB), have emerged as crucial players of memory storage, and their disruption accompanies many cognitive disabilities. However, a molecular link that can influence these major players and can be a potential recovery target has been elusive. Recent reports suggest that extracellular cues at the synapses might evoke an intracellular signaling cascade and regulate memory function. Herein, we report novel function of an extracellular serine protease, kallikrein 8 (KLK8/Neuropsin) in regulating the expression of microtubule associated dendrite growth marker microtubule-associated protein (MAP2)c, dendrite architecture and protein kinase A (PKA)-CREB signaling. Both knockdown of KLK8 via siRNA transfection in mouse primary hippocampal neurons and via intra-hippocampal administration of KLK8 antisense oligonucleotides in vivo reduced expression of MAP2c, dendrite length, dendrite branching and spine density. The KLK8 mediated MAP2c deficiency in turn inactivated PKA and downstream transcription factor phosphorylated CREB (pCREB), leading to downregulation of memory-linked genes and consequent impaired memory consolidation. These findings revealed a protease associated novel pathway of memory impairment in which KLK8 may act as a "regulator of regulators", suggesting its exploration as an important therapeutic target of memory disorders. © 2018 The Author(s).
Acquiring preferred mode of aggregation through positional antagonism for saponification triggered gelation
(Royal Society of Chemistry, 2023) Prem Chand; Ashish Kumar
A substituent mediated change in the mode of aggregation during saponification triggered transformation of two ester-containing ZnII-complexes (A-B) into metallogels (MGA-MGB) has been presented. Structures of A and B have been inspired by reported complexes 1 and C4, which exhibited gelation via the saponification triggered method. A consists of an additional -OCH3 group compared to 1, while B and C4 are structural isomers, i.e., identical except one positionally altered -OCH3. During gelation, 1 and C4 exhibited ‘J-aggregation’, but herein, in similar conditions, A and B significantly acquire ‘H-aggregation’, leading to the formation of metallogels. This discrepancy has been addressed for the first time, which signified that gelators with isomeric dissimilarity acquired different modes of aggregation toward gelation. A distinguishing role of particular substituents has been revealed for a suitable mode of aggregation for this class of gelation, which is designated as ‘positional antagonism’. This has been susbtantiated by UV-vis, fluorescence, and 1H-NMR spectroscopy as well as AFM, SEM, rheological, and DFT studies. © 2023 The Royal Society of Chemistry.
An unconventional mechanistic insight on aggregation induced emission in novel boron dipyrromethenes and their rational biological realizations
(American Chemical Society, 2016) Roop Shikha Singh; Ashish Kumar; Sujay Mukhopadhyay; Gunjan Sharma; Biplob Koch; Daya Shankar Pandey
Quinolone and quinoline based boron dipyrromethenes (BODIPYs) viz. BQN1 and BQN2 obtained by relative stabilization of keto and enol forms of N-methylated quinolones via minute substitutional variations (-H/-OCH3) have been reported. The relative disparity in degree of aromaticity arising from quinolone/quinoline strongly affects the free rotation of these molecules. The photophysical and structural characteristics of these compounds revealed an exceptional dissonance between restriction of intramolecular rotation (RIR) and aggregation induced emission (AIE) signifying competitive steric hindrance and conjugation. Despite being an AIE inactive dye, BQN1 experiences maximum RIR and excels as a viscosity sensitive hindered molecular rotor, while an effective J-aggregation irrevocably established AIE in BQN2. This is the first report dealing with utilization of AIE active BODIPY (BQN2) in fabrication of AIEgen loaded bovine serum albumin (BSA) nanoparticles with live cell imaging in human breast cancer cell line MDA-MB-231. Binding mode of human serum albumin (HSA) to BQN2 has also been determined by molecular docking studies. In addition, viscochromism of BQN1 has been visualized through apoptotic marking in the MDA-MB-231 cell line. © 2016 American Chemical Society.
Analysis of Presenilin 1 and 2 interacting proteins in mouse cerebral cortex during development
(Elsevier Ltd, 2014) Ashish Kumar; M.K. Thakur
In our previous report, we showed that Presenilin (PS)1 and 2 have differential expression profile from early embryonic stages till adulthood in mouse cerebral cortex, suggesting that both of these proteins are crucial for brain development. Genetic manipulation studies have also shown the involvement of PS1 in brain development, but PS2 remains largely unexplored. In order to understand how PS1 and 2 mediate developmental functions, we have investigated the interaction of PS1 and 2 with proteins of mouse cerebral cortex during development. Co-immunoprecipitation (Co-IP) combined with MALDI-MS/MS analysis revealed 12 interacting partners of PS1 and 11 partners of PS2. The interacting proteins were different for PS1 and 2, and involved in cell division, glycolysis, cell adhesion and protein trafficking. Densitometric analysis of protein bands visualized after SDS-PAGE separation of Co-IP proteins revealed variation in their amount and degree of interaction during different developmental stages of mice. Further, immunoblot based validation of PS1 interacting protein Notch-1 showed maximum interaction at embryonic day (E) 12.5, decline at E18.5, upregulation from postnatal day 0 (P0) to P20 and thereafter reduction at P45 and 20 weeks. In-silico analysis of PS and its interacting proteins indicated conformation based interaction through common type of secondary structures having alpha helical, extended beta strand and random coil, and CK2, PKC phosphorylation and myristoylation motifs. Taken together, our study showed that PS1 and PS2 interact to varying extent with different proteins of mouse cerebral cortex and suggests their interaction based on specific conformation and involvement in diverse functions essential for the brain development. © 2014 ISDN.
Anion triggered metallogels: Demetalation and crystal growth inside the gel matrix and improvement in viscoelastic properties using Au-NPs
(Royal Society of Chemistry, 2016) Arnab Biswas; Mrigendra Dubey; Sujay Mukhopadhyay; Ashish Kumar; Daya Shankar Pandey
Progelator complex Zn-TRPA-2 undergoes Cl- triggered gelation to afford ZTP2G, while Zn-TRPA-2 capped Au-NPs under similar conditions gave another gel GNZTP2G which also represents a rare nano-composite metallogel. When Zn-TRPA-2 was triggered by Cl- and NO3- simultaneously, crystals of demetalated species NA-TRPA-2 grew inside the ZTP2G matrix. Interestingly, GNZTP2G exhibits superior viscoelastic properties over ZTP2G. © The Royal Society of Chemistry 2016.
Application of deep learning models for accurate classification of fluid collections in acute necrotizing pancreatitis on computed tomography: a multicenter study
(Springer, 2024) Pankaj Gupta; Ruby Siddiqui; Shravya Singh; Nikita Pradhan; Jimil Shah; Jayanta Samanta; Vaneet Jearth; Anupam Singh; Harshal Mandavdhare; Vishal Sharma; Amar Mukund; Chhagan Lal Birda; Ishan Kumar; Niraj Kumar; Yashwant Patidar; Ashish Agarwal; Taruna Yadav; Binit Sureka; Anurag Tiwari; Ashish Verma; Ashish Kumar; Saroj K. Sinha; Usha Dutta
[No abstract available]
Arsenic exposure to mouse visceral leishmaniasis model through their drinking water linked to the disease exacerbation via modulation in host protective immunity: a preclinical study
(Nature Research, 2023) Ghufran Ahmed; Fauzia Jamal; Ritesh K. Tiwari; Veer Singh; Sachchida Nand Rai; Sanjay K. Chaturvedi; Krishna Pandey; Santosh K. Singh; Ashish Kumar; Shyam Narayan; Emanuel Vamanu
A large body of evidence has shown a direct link between arsenic exposure and drug resistance to Leishmania parasites against antimonial preparations in visceral leishmaniasis (VL) hyper-endemic regions, especially in India and its sub-continent. However, the implicated roles of arsenic on the VL host, pathophysiological changes, and immune function have not yet been clarified, particularly at the reported concentration of arsenic in the VL hyper-endemic area of Bihar, India. Herein, we exposed the mouse VL model to arsenic (0.5 mg/L to 2 mg/L) through their drinking water and analyzed its effect on T cells proliferation, Th1/Th2-mediators, MAPK signaling cascade, and parasite load in preclinical models. Coherently, the parasite count in Giemsa stained spleen imprint has been investigated and found significant positive associations with levels of arsenic exposure. The liver and kidney function tests (AST, ALT, ALP, BUN, Creatinine, Urea, etc.) are apparent to hepatonephric toxicity in arsenic exposed VL mice compared to unexposed. This observation appears to be consistent with the up-regulated expression of immune regulatory Th2 mediators (IL-4, IL-10, TGF-β) and down-regulated expression of Th1 mediators (IL-12, IFN-γ, TNF-α) with a suppressed leishmanicidal function of macrophage (ROS, NO, iNOS). We also established that arsenic exposure modulated the host ERK-1/2 and p38 MAPK signaling cascade, limited T lymphocyte proliferation, and a lower IgG2a/IgG1 ratio to favor the Leishmania parasite survival inside the host. This study suggests that the contorted Th1-subtype and exacerbated Th2-subtype immune responses are involved in the increased susceptibility and pathogenesis of Leishmania parasite among subjects/individuals regularly exposed to arsenic. © 2023, The Author(s).
Assessment of hydrologic impact on flow regime due to dam inception using IHA framework
(Springer Science and Business Media Deutschland GmbH, 2023) Ashish Kumar; Vinod Kumar Tripathi; Pradeep Kumar; Amitava Rakshit
In the last century, thousands of dams and diversions have been built to regulate the streamflow, resulting in water impoundment in the upstream and frequent drought conditions in the downstream. It has pressured researchers to study flow regime change and its complication on the downstream biota. The present study planned to develop a framework for trend analyzing of river flow and detecting flow regime change after the inception of Isapur and Arunavati dams, situated on the upstream side of Penganga bridge. Mann–Kendall (MK) and Sen’s slope estimator for trend analysis and Indicators of Hydrologic Alteration (IHA) for flow regime alteration analysis were utilized. A total 26 parameters showed negatively altered flow regime with a magnitude varying from − 5.56 to − 100%. Fourteen altered parameters were modified drastically (more than 50% decrease) with the highest modification in 30-day maximum (100%) post-single dam inception. a total of 13 parameters were negatively altered with alteration value − 9.09 to − 86.36% post-double dam inception, out of which, three parameters were severely altered, with the highest alteration in the month of June. The period (1983–1994) was more altered than 1995–2016. This shows that Isapur dam has higher impact on flow regime change than Arunavati dam. Information about alteration of hydrological parameters will be helpful to improve the water flow regulation at Isapur and Arunavati dams for restoring river ecology on the downstream side. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Association of thrombocytopenia and liver enzymes in canine monocytic ehrlichiosis: a meta-analysis
(Springer, 2025) Ashish Kumar; Ambika Sharma; Vikas Kumar; Megha Agrawal; Kalpana Tiwari; Chahat Choudhary; Gyan Vardhan
Canine Ehrlichiosis, caused by Ehrlichia canis and transmitted through the brown dog tick (Rhipicephalus sanguineus), poses a significant health challenge to dogs in India, where the warm climate favors tick proliferation. This study employs a meta-analytical approach to analyze the clinical and biochemical markers of Canine Monocytic Ehrlichiosis (CME) over the past decade (2014–2024) across India. The objective is to assess the diagnostic value of thrombocytopenia and elevated liver enzymes aspartate transaminase, alanine transaminase, and alkaline phosphatase (AST, ALT, ALP) in dogs affected by CME. Following PRISMA guidelines, 13 relevant studies were selected after screening 2,018 publications. Data were pooled to evaluate the associations between biochemical markers and CME. The meta-analysis found moderate associations between thrombocytopenia and CME (SMD = 0.34, I2 = 94.5%) and stronger correlations with elevated liver enzymes: ALT (SMD = 2.47, I2 = 94.0%), AST (SMD = 2.23, I2 = 94.3%), and ALP (SMD = 2.31, I2 = 91.9%). High heterogeneity among studies was noted, but the findings underscore the importance of these biochemical markers in CME diagnosis. Meta-influence analyses confirmed the robustness of the results, with no individual study disproportionately affecting the pooled estimates. Publication bias tests, including Egger’s and Begg’s, revealed no significant bias, ensuring the reliability of the conclusions. These findings highlight the critical role of liver enzyme evaluations in diagnosing CME, while thrombocytopenia remains a supplementary marker. This study contributes to a more standardized understanding of CME’s clinical diagnosis and emphasizes the need for further research to reduce variability in future studies. © Indian Society for Parasitology 2025.
Binding of transcription factors to Presenilin 1 and 2 promoter cis-acting elements varies during the development of mouse cerebral cortex
(Elsevier Ireland Ltd, 2016) Ashish Kumar; M.K. Thakur
Previously, we reported differential expression of Presenilin (PS)1 and 2 and epigenetic modifications of their gene promoter in the cerebral cortex of mice during development. We identified the crucial role of DNA methylation and H3K9/14 acetylation in stage specific PS expression during brain development. Interestingly, we noted differential DNA methylation in putative binding sites of transcription factors considered pivotal for brain development. This prompted us to study the binding of transcription factors to cis-acting elements of PS1 and PS2 promoter in the cerebral cortex of mice during development. In-silico analysis revealed various cis-acting elements of PS1 and PS2 promoter and their putative transcription factors. We selected those cis-acting elements that were proven by wet lab experiments to interact with the transcription factors crucial for brain development. Electrophoretic mobility shift assay revealed that the binding of nuclear proteins to PS1 promoter cis-acting elements like HSF-1, Cdx1, Ets-1 and Sp1 significantly increased at embryonic day (E) 12.5, postnatal day (P) 45 and 20 weeks (w) as compared to P0. The binding pattern of these factors correlated well with the PS1 expression profile, indicating their cumulative influence on PS1 gene transcription. For PS2 promoter, the binding of Nkx2.2 and HFH-2 was high at prenatal stages (E12.5 and E18.5) while that of Cdx1 and NF-κB was maximum at postnatal stages (P45 and 20w). Taken together, our study shows that the binding of HSF-1, Cdx1, Ets-1 and Sp1 to PS1 promoter and that of Nkx2.2, HFH-2, Cdx1 and NF-κB to PS2 promoter regulate their differential expression during brain development. © 2016 Elsevier Ireland Ltd.
Biphasic electropolymerization of polyaniline-multiwalled carbon nanotube nanocomposite
(Nova Science Publishers, Inc., 2013) Monika Srivastava; Ashish Kumar; Bhavana Gupta; Sanjay K. Srivastava; Rajiv Prakash
Despite the tremendous research on conjugated polymers to date, polyaniline, PAni and its derivatives are the most interesting conjugated polymers due to their unique electrochemical properties, easy polymerization, low cost and wide range of application. In the recent years polymer composites formation with various nanofillers are explored to enhance the various properties of the polymers. Multi-walled carbon nanotube, MWNT is one of the well-known nanofillers for its excellent electrical, mechanical and thermal properties. Besides all properties, the processability, stability and solubility hinder its commercial utilization and fabrication of devices. To overcome these limitations, coating of PAni over MWNTs is one of the possible ways to obtain the high performance of the resulted nanocomposite towards device applications. Although various strategies have been developed to produce such nanocomposites (i.e. polymer supported by conducting templates) but still the homogeneity/uniformity of nanocomposite and stability are the major challenges. Though the electrochemical polymerization technique suffers from various limitations, it is still a good approach for the uniform and thin film formation. However, formation of composites is rather difficult as the fillers may not be electroactive and also may not form homogeneous suspension (or colloidal state) in the electrolytes in which monomers are dissolved. Therefore, the distribution of fillers in the polymer matrixes is difficult to control using conventional electrochemical methods. We proposed a biphasic electropolymerization method as an efficient approach for polymerization of monomers with nanofillers to get uniform and homogeneous polymercomposites. This technique not only provides a better selection of solvents for monomers and fillers but also better control of diffusion and kinetics. In this chapter, electrochemical techniques used for synthesis with the latest development in the electrochemical synthesis of PAni nanocomposite is described with our novel biphasic electropolymerization technique for multi-walled carbon nanotubepolyaniline (MWNT-PAni) nanocomposite. MWNT-PAni nanocomposite formation, based on the biphasic electropolymerization technique, provides a general method for the formation of uniform nanocomposites for other polymers and fillers. © 2013 by Nova Science Publishers, Inc. All rights reserved.
Can enantiomer ligands produce structurally distinct homochiral MOFs?
(Royal Society of Chemistry, 2015) Mrigendra Dubey; Ashish Kumar; Vishal M. Dhavale; Sreekumar Kurungot; Daya Shankar Pandey
Here, we report a self-assembled homochiral metal-organic framework [Cu1.5(H2Ll-leu)(Ac)H2O]n·3H2O (1) obtained from an l-leucine-derived ligand (H4Ll-leu) and Cu(Ac)2·H2O in a 1 : 1 ratio. Coordination-induced conformational change in the ligand has been monitored by circular dichroism which has been further attested by synthesizing a d-leucine-containing enantiomer H4Ld-leu and its Cu(ii) complex [Cu1.5(H2Ld-leu)H2O]n·10H2O (2). Structure determination revealed entirely different structures for the homochiral MOFs (1 and 2) obtained from the l/d-leucine-derived enantiomer ligands under analogous reaction conditions. Further, structural dissimilarity in these MOFs has been judicially supported by proton conductance studies. MOF 1 shows higher proton (10-5 S cm-1) conductance in comparison to 2 (10-6 S cm-1) due to dissimilar alignment of the hydrogen-bonded water molecules in the hydrophilic pocket as well as crystal packing. © The Royal Society of Chemistry.
Capability assessment of conventional and data-driven models for prediction of suspended sediment load
(Springer Science and Business Media Deutschland GmbH, 2022) Ashish Kumar; Vinod Kumar Tripathi
Information about suspended sediment concentration (SSC) in the stream is vital for sustainability of water conservation and erosion control planning, designing and monitoring. In this research, prediction of SSC has been done using artificial neural network (ANN), support vector regression (SVR) and multi-linear regression (MLR) models. Performance evaluation of developed models has been carried out on the basis of root mean square error (RMSE), correlation coefficient (r), coefficient of efficiency (CE) and pooled average relative error (PARE). Cross-correlation function (CCF) validated that gamma test (GT) is an appropriate tool for the selection of most responsive input variables. On the basis of GT and CCF, GT-6 model was selected as the model with most effective input variables, with the values of gamma, standard error and V-ratio as 0.0643, 0.00583 and 0.2570, respectively. The ANN (6–3-1) model performed better than the other single and double hidden layered ANN models with the values of r, RMSE, CE and PARE as 0.939, 0.0063 g/l, 85.17 and 0.0160, respectively. The performance of the SVR model was found better with the values of r, RMSE, CE and PARE as 0.906, 0.018 g/l, 79.09 and 0001, respectively, but slightly poor than the selected ANN (6–3-1) model. The values of r, RMSE, CE and PARE were found as 0.899, 0.0312 g/l, 65.15 and − 0.0031, respectively, in the case of MLR model. The present study revealed that among the ANN, SVR and MLR models, the ANN model with a single hidden layer is most suitable for observed SSC. The present study offers the simple efficient model to estimate the suspended sediment concentration in the stream with minimum error using limited data set. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Cationic Ru(II), Rh(III) and Ir(III) complexes containing cyclic π-perimeter and 2-aminophenyl benzimidazole ligands: Synthesis, molecular structure, DNA and protein binding, cytotoxicity and anticancer activity
(Elsevier, 2016) Amit Kumar; Ashish Kumar; Rakesh Kumar Gupta; Rajendra Prasad Paitandi; Krishna Beer Singh; Surendra Kumar Trigun; Maninder Singh Hundal; Daya Shankar Pandey
Synthesis, characterization, DNA and protein binding as well as anticancer activity of the organometallic complexes [(η6-C6H6)RuCl(APBI)]Cl (1), [(η6-p-MeC6H4Pri)RuCl(APBI)]Cl (2), [(η6-C6Me6)RuCl(APBI)]Cl (3), [(η5-C5Me5)RhCl(APBI)]Cl·H2O (4) and [(η5-C5Me5)IrCl(APBI)]Cl·H2O (5) containing 2-aminophenyl benzimidazole (APBI) have been described. The complexes 1-5 exhibited strong DNA, protein binding and anticancer activity against cervical cancer (SiHa) cell line. Their binding with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) have been examined by absorption and emission spectral studies. Strong interactions between complexes and CT-DNA have been affirmed by absorption spectral and EthBr displacement studies, while interaction with BSA via static quenching explored by fluorescence titration, synchronous and 3D fluorescence spectroscopy. The interactions between 1-5 and DNA has also been scrutinized by 1H NMR spectral studies using guanosine as a model for DNA. These results have been supported by DFT calculations and molecular docking studies. Cytotoxicity, apoptosis and in vitro anticancer activity of 1-5 toward SiHa cell line have been investigated by MTT assay and acridine (AO)/ethidium bromide (EthBr) fluorescence staining. Overall results revealed that DNA and protein binding, as well as anticancer activity of 1-5 follows the order as 5 > 3 > 2 > 1 > 4. © 2015 Elsevier B.V. All rights reserved.