Browsing by Author "Deepak"

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Adsorption-desorption behaviour of arsenic on naturally occurring clay-organic complexes in an Alfisol and Inceptisol
(Springer, 2025) Deepak; Ruma Das; Debasis Golui; Nayan Ahmed; Ramswaroop Bana; Amrit Kumar Jha; Siba Prasad Datta
The adsorption-desorption characteristics of arsenic (As) in soil may affect its mobility, bioavailability, and potential toxicity. While As adsorption behaviour in soil has been thoroughly studied, very little is known about the interactions of As with clay-sized fractions present in soils, including clay-organic complexes (COC), clay-oxides, and clay. In this study, we investigated the adsorption and desorption behaviour of As on clay-sized fractions as a function of As concentration, pH, and temperature in two different soil orders, namely Alfisol and Inceptisol. Naturally occurring COC were isolated from bulk soil using density fractionation, while clay–oxides and clay fractions were obtained through selective chemical dissolution methods. Batch adsorption–desorption experiments of As were then conducted under controlled laboratory conditions. The adsorption data exhibited a strong fit to both the Langmuir (r = 0.95–0.99) and Freundlich (r = 0.97–0.99) isotherm models. The adsorption of As on the clay-sized fractions from both Alfisol and Inceptisol was exothermic (-∆H° = 13.7 to 34.3 kJ mol− 1) and spontaneous. Between the two soil orders, Alfisol had better As retention at the acidic pH (5.5) at 298 K. Among the clay-sized fractions, clay–oxides in Alfisol and COC in Inceptisol exhibited the highest As adsorption capacities (qmax) i.e., 588 and 344 µg g− 1, respectively. The Al-Fe oxides played a dominant role in As adsorption–desorption in Alfisol, whereas organic matter was more influential in Inceptisol. The desorption efficiency was higher in Inceptisol and the desorption index (DI) revealed comparatively higher hysteresis (DI > 1) for COC in Alfisol and Inceptisol and clay-oxides in Alfisol. These findings enhance understanding of the contrasting roles of Al–Fe oxides and organic matter to regulate As retention and desorption at varying temperature and pH, providing valuable insight for predicting As mobility and developing soil-specific management strategies to ensure environmental safety and sustainable agricultural production. © The Author(s) under exclusive licence to Society for Environmental Sustainability 2025.
Correction: Adsorption-desorption behaviour of arsenic on naturally occurring clay-organic complexes in an Alfisol and Inceptisol (Environmental Sustainability, (2025), 8, 4, (715-729), 10.1007/s42398-025-00384-6)
(Springer, 2025) Deepak; Ruma Das; Debasis Golui; Nayan Ahmed; Ramswaroop Bana; Amrit Kumar Jha; Siba Prasad Datta
In this article year of publication for Reference “Wang S, Mulligan, CN (2006). Effect of natural organic matter on arsenic release from soils and sediments into groundwater. Environ Geochem Health 28 (3): 197–214.” was incorrectly given as 2009. Consequently, the citation “Wang and Mulligan 2009” has also been corrected to “Wang and Mulligan 2006” in section “Effect of organic matter and Al-Fe oxides on As adsorption by clay-sized fractions”. The original article has been corrected. © The Author(s) under exclusive licence to Society for Environmental Sustainability 2025.
Developing a nontoxic and biocompatible polymeric self-assembly by using RAFT methodology for biomedical application
(Elsevier Ltd, 2019) Deepak; Swati Sharma; Ashok Kumar; Rajesh Kumar; Koushik Nandy; Arti Srivastava; Munendra Singh Tomar; Arbind Acharya
The amphiphilic block copolymer poly(N-vinylpyrrolidone)-b-poly(N-vinylcarbazole) (PVP-b-PVK) was synthesized by reversible-deactivation radical polymerization (RDRP)using reversible addition-fragmentation chain transfer (RAFT) methodology by new chain transfer agent (CTA) i.e. benzyl piperidine dithiocarbamate (BPDC). The pseudo-first-order kinetics and linear evolution of the molar mass with N-vinylpyrrolidone (NVP) conversion were obtained with the molar mass dispersity (Ð) 1.30–1.41 in toluene. 1H NMR spectrum indicates the presence of chain-end functional groups on homopolymer and block copolymer. The above block copolymer get self-assembled and form micelles in the aqueous medium, the size of micelles is characterized by 1H NMR, transmission electron micrographs (TEM) and dynamic laser light scattering (DLS) analyses, and critical micelles concentration (CMC) was determined by UV–vis spectroscopy. Trypan blue exclusion and MTT assay were done to ensure the cytotoxic effect of PVP-b-PVK on different types of normal cells (thymocytes, splenocytes and macrophage), and no cytotoxic effect was shown by block copolymer on cells, while observed biocompatibility with cells was 200 mg/mL. Further, the beads of block copolymer releases (65%) highly water-soluble levofloxacin drug up to 8 h in a controlled manner at pH 7.4 (37 ± 0.2 °C), while loading of levofloxacin drug was 62% (w/w). © 2018 Elsevier Ltd
Development of a novel chitosan based biocompatible and self-healing hydrogel for controlled release of hydrophilic drug
(Elsevier B.V., 2018) Swati Sharma; Ashok Kumar; Deepak; Rajesh Kumar; Nishant Kumar Rana; Biplob Koch
Smart polymeric hydrogels of chitosan and acryloyl-phenylalanine having potential of fast intrinsic shape memory properties (self-healing), non-toxic, biocompatible with moderate mechanical strength have been developed. The hydrogel has been formed by linking its network with flexible pendant side chains of chitosan and acryloyl-phenylalanine (exhibiting optimal balance of hydrophilic and hydrophobic moieties). The non-toxic and biocompatible behavior of the synthesized chitosan based hydrogel reveals its potential use towards the biomedical field. The side chain of hydrogel consists of amine and carboxylic acid groups and these moieties allow non-covalent interactions (H-bonding) across its interface. Thus, synthesized hydrogel shows very good self-healing property. Further, it has shown remarkable swelling (at different pH viz.- 2, 7, 9), cell viability (HEK-293 cells up to 200 μg/mL), cell proliferation, and controlled drug release and thus found multi-responsive. © 2018 Elsevier B.V.
Development of graft copolymer of carboxymethylcellulose and N-vinylcaprolactam towards strong antioxidant and antibacterial polymeric materials
(Elsevier B.V., 2018) Ashok Kumar; Deepak; Swati Sharma; Shere Afgan; Rajesh Kumar; Anand Kumar Keshari; Ragini Srivastava
The present paper reports graft copolymerization of N-vinylcaprolactam (NVCL) onto carboxymethylcellulose (CMC) using tert-butyl hydroperoxide (TBHP) initiator in N2 atmosphere. The grafting was found to be highest when concentrations of CMC, NVCL and TBHP were 6.25 × 10−2 g dm−3, 10 × 10−3 mol dm−3 and 20 × 10−5 mol dm−3 respectively. The graft copolymer (CMC-g-PNVCL-1) was characterized by FTIR, 1HNMR, SEM, AFM, XRD and TGA analysis. The antioxidant activity of the graft copolymer was found to be higher (3.81%) than CMC and slightly less (5.47%) than the standard one (butylated hydroxytoluene, BHT). The hydroxyl radical scavenging activity of graft copolymer was found to be slightly less (13.69%) than CMC and more (44.20%) than the BHT. The hydrogen peroxide scavenging activity of graft copolymer was observed to be less (20.42%) than CMC and 53.34% less than BHT. The superoxide scavenging activity of graft copolymer was greater than the both. Compared to CMC the graft copolymer has shown greater antibacterial activity against S. aureus, Proteus vulgaris and S. typhi bacteria and less against Klebsiella pneumonia and Salmonella typhimurium. © 2018 Elsevier B.V.
Fabrication of a metal clad planar polymer waveguide based sensor for detection of low-refractive-index-contrast of liquid
(Elsevier GmbH, 2017) Gulab Chand Yadav; Gaurav Sharma; Sushil Kumar; Deepak; Rajesh Kumar; Surendra Prasad; Vivek Singh
A four layer polymer film based planar waveguide having a metallic clad is fabricated and analysed. The fabricated waveguide is validated for detection of small variation in the refractive index of aqueous media solution. It is observed that with increase of refractive index of aqueous media solution, the mode coupling angle of incident light increases. As the thickness of polymer film is increased from 810 nm to 1650 nm, this mode coupling angle is shifted toward higher angle of incidence. The angular interrogation of our fabricated waveguide shows that the maximum obtained sensitivity is 30 deg/RIU for 810 nm polymer film waveguide. Also, our analysis shows that the obtained experimental results are in good agreement with theoretical results. © 2017 Elsevier GmbH
High-Pressure and ultrahigh-temperature metamorphism at Diguva Sonaba, Eastern Ghats Mobile Belt (India): New constraints from phase equilibria modelling
(Capital Publishing Company, 2014) Divya Prakash; Deepak
The investigated area around Diguva Sonaba represents a part of granulite facies terrain of Eastern Ghats Mobile Belt (India). The Precambrian metamorphic rocks of the area consist of mafic granulite (± garnet), khondalite, leptynite (± garnet, biotite), charnockite, enderbite, calc-granulite, migmatic gneiss and sapphirine-spinel-bearing granulite, which comprise the major rock types of the area. Sapphirine-spinel-bearing granulite occurs as lenticular bodies in khondalites, leptynites and calc-granulites. Textural relations such as presence of corroded blebs of biotite within garnet and orthopyroxene, resorbed hornblende within pyroxenes, and coarse prisms of sillimanite presumably pseudomorphs after kyanite, provide evidence of either, an earlier episode of upper amphibolites facies metamorphism or represent relict of a single prograde event leading to granulites facies metamorphism. In the sapphirine-spinel granulite, osumilite and sapphirine + spinel + quartz were stable during the thermal peak of granulite facies metamorphism (early stage) but were later replaced by the (Crd-Opx-Qtz-Kfs)-symplectites and variety of reaction coronas respectively during the retrograde episode (middle stage). Variable amounts of retrograde biotite or biotite + quartz symplectite replace orthopyroxene, cordierite, (Opx-Crd-Kfs-Qtz)-symplectite (late stage). The prograde path was followed by peak metamorphism at a temperature of c. 1000 °C and a pressure of c. 12 kbar as computed by isopleths of XMg garnet and XAlorthopyroxene. The sequence of reactions as deduced from the corona and symplectites assemblages, together with petrogenetic grid and pseudosection considerations, records a clockwise P-T evolution. © 2014, Capital Publishing Company.
L-Alanine induced thermally stable self-healing guar gum hydrogel as potential drug vehicle for sustained release of hydrophilic drug
(Elsevier Ltd, 2019) Swati Sharma; Shere Afgan; Deepak; Ashok Kumar; Rajesh Kumar
A simple approach for preparing self-healable guar gum-graft-acrylic acid (GG-PAA) hydrogel using L-alanine as a cross-linking agent was introduced for the first time. It drastically modifies the mechanical strength of the hydrogel to G′ = 90,570 Pa. Thus, a series of guar gum (GG) based hydrogel was synthesized by varying the concentration of L-alanine from 0.4 to 1% w/v. The hydrogel was characterized by different analytical techniques such as FTIR, HRSEM etc. The mechanical strength of the hydrogel was investigated by rheology analysis and it was observed in terms of storage and loss modulus i.e. G′ & G′′, respectively. Maximum G′ & G′′ (90,560 Pa & 60,820 Pa) were observed when 1 wt% of L-alanine was used as a cross-linking agent. This GG based hydrogel have shown excellent swelling i.e. up to 3350%, which indicates its porous network. The synthesized hydrogel has been identified as a controlled drug delivery gel, which releases 98% of the highly water-soluble loaded drug in 140 h. © 2019 Elsevier B.V.
Reaction textures and metamorphic evolution of sapphirine-spinel-bearing and associated granulites from Diguva Sonaba, Eastern Ghats Mobile Belt, India
(Cambridge University Press, 2014) Divya Prakash; Deepak; Praveen Chandra Singh; Chandra Kant Singh; Suparna Tewari; Makoto Arima; Hartwig E. Frimmel
The Diguva Sonaba area (Vishakhapatnam district, Andhra Pradesh, South India) represents part of the granulite-facies terrain of the Eastern Ghats Mobile Belt. The Precambrian metamorphic rocks of the area predominantly consist of mafic granulite (±garnet), khondalite, leptynite (±garnet, biotite), charnockite, enderbite, calc-granulite, migmatic gneisses and sapphirine-spinel-bearing granulite. The latter rock type occurs as lenticular bodies in khondalite, leptynite and calc-granulite. Textural relations, such as corroded inclusions of biotite within garnet and orthopyroxene, resorbed hornblende within pyroxenes, and coarse-grained laths of sillimanite, presumably pseudomorphs after kyanite, provide evidence of either an earlier episode of upper-amphibolite-facies metamorphism or they represent relics of the prograde path that led to granulite-facies metamorphism. In the sapphirine-spinel-bearing granulite, osumilite was stable in addition to sapphirine, spinel and quartz during the thermal peak of granulite-facies metamorphism but the assemblage was later replaced by Crd-Opx-Qtz-Kfs-symplectite and a variety of reaction coronas during retrograde overprint. Variable amounts of biotite or biotite+quartz symplectite replaced orthopyroxene, cordierite and Opx-Crd-Kfs-Qtz-symplectite at an even later retrograde stage. Peak metamorphic conditions of c. 1000°C and c. 12 kbar were computed by isopleths of XMg in garnet and XAl in orthopyroxene. The sequence of reactions as deduced from the corona and symplectite assemblages, together with petrogenetic grid and pseudosection modelling, records a clockwise P-T evolution. The P-T path is characteristically T-convex suggesting an isothermal decompression path and reflects rapid uplift followed by cooling of a tectonically thickened crust. Copyright © Cambridge University Press 2014.
Stimuli-Responsive Polymeric Hydrogel-Copper Nanocomposite Material for Biomedical Application and Its Alternative Application to Catalytic Field
(Wiley-Blackwell, 2017) Swati Sharma; Deepak; Ashok Kumar; Shere Afgan; Rajesh Kumar
Naturally occurring non-toxic, biocompatible chitosan based hydrogel nanocomposite with copper nanoparticle was synthesized via in-situ free radical polymerization using chitosan (CS) as substrate, acrylamide (Am) as monomer, copper nanoparticles (CuNPs), ammonium persulphate as an initiator and glutaraldehyde as a cross-linking agent. The synthesized CS-PAm-CuNPs hydrogel nanocomposite was characterized by rheology studies, HRSEM & FT-IR spectroscopy. It shows excellent swelling up to 300% in wide range of pH of 3–9 with good mechanical strength (exhibit 1380% stain value). Further, synthesized hydrogel nanocomposite was found to be a multi-responsive due biomedical application and alternative application to catalytic field. The synthesized hydrogel-nanocomposite showed 96% release of highly water soluble levofloxacin antibiotic drug in blood serum in controlled manner up to 30 h and its catalytic activity (90%). Successful reduction of 4-nitrophenol into 4-aminophenol in presence of hydrogel nanocomposite confirms its Catalytic property. This hydrogel nanocomposite catalyst was found to be ecofriendly and it can be reused after washing it with distilled water. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Studies on non-gelatinous & thermo-responsive chitosan with the N-isopropylacrylamide by RAFT methodology for control release of levofloxacin
(Elsevier B.V., 2020) Deepak; Shere Afgan; Krishtan Pal; Rajesh Kumar
The non-gelatinous and thermo-responsive properties were introduced in chitosan by incorporating the chain of poly(N-isopropylacrylamide) via reversible addition-fragmentation chain transfer (RAFT) polymerization. To achieve this, the reaction was carried out at 80 °C by modifying the chitosan(CS) with RAFT agent as a macroinitiator (CS-RAFT), where the amine group of CS was protected with phthalic anhydride and then reacted with 4-cyano-4-[(dodecyl sulfanyl thiocarbonyl)sulfanyl]-pentanoic acid (CDSTSP) to form CS-RAFT agent. Further, the addition of NIPAAm chains onto CS-RAFT was carried out in N,N′-dimethylformamide (DMF) solvent by using 2,2′-azobisisobutyronitrile (AIBN) as an initiator in N2 atmosphere. The controlled addition of NIPAAm chains on to CS was confirmed by 1H NMR spectroscopy, further, a kinetic study was performed to get the characteristic features of the RAFT reaction. The product was characterized by 1H NMR, FT-IR, UV–Visible spectroscopy, XRD, SEM, and TGA analyses. The product in aqueous solution showed LCST at 2.0 mg/mL on 33 ± 0.1 °C. Further, beads were prepared with the sodium alginate and loaded the water-soluble levofloxacin drug (60% w/w loading was achieved). The drug delivery process was studied in-vitro at 37 ± 0.1 °C & pH 7.4, which shown controlled release of drug up to 32 h and it was 71% of the loaded levofloxacin. © 2020 Elsevier B.V.
Synthesis of xanthan gum graft copolymer and its application for controlled release of highly water soluble Levofloxacin drug in aqueous medium
(Elsevier Ltd, 2017) Ashok Kumar; Deepak; Swati Sharma; Arti Srivastava; Rajesh Kumar
Graft copolymers (XG-g-PNVP-1 to XG-g-PNVP-5) of xanthan gum (XG) and poly(N-vinyl-2-pyrrolidone) (PNVP) was synthesized by free radical polymerization using peroxymonosulphate/thiourea redox pair. The synthesized graft copolymers were well characterized by 1H NMR, FTIR, XRD, SEM, TGA/DTA and AFM analyses. The optimum conditions for maximum grafting were determined by varying the concentrations of N-vinyl-2-pyrrolidone (NVP) from 10 × 10−2 to 18 × 10−2 mol dm−3; the grafting ratios increases up to 14 × 10−2 mol dm−3, while thereafter decreased. Graft copolymer (XG-g-PNVP-D) hybrid was prepared to load levofloxacin drug, about 15 mg drug was loaded; and its release was studied in phosphate buffer solution (PBS) at pH 7.4 on 37 ± 0.1 °C; About 80% drug was released in 36 h. © 2017 Elsevier Ltd
The benzyl ethyl trithiocarbonate mediated control synthesis of a block copolymer containing N-vinyl pyrrolidone by RAFT methodology: Influence of polymer composition on cell cytotoxicity and cell viability
(Elsevier Ltd, 2020) Koushik Nandy; Arti Srivastava; Shere Afgan; Deepak; Rajesh Kumar; Arun Kumar Rawat; Rajan Singh; Rakesh K. Singh
Benzyl ethyl trithiocarbonate (BET) mediated reversible addition–fragmentation chain transfer (RAFT) polymerization was carried out in dry 1,4-dioxane medium at 85 °C to synthesize Poly(n-Butyl Acrylate) (PBA) with pre-determined molecular weight (Mn 7999), narrow polydispersity (PDI 1.13) and precise chain end structure. The end chain functionality of macro chain transfer agent (CTA) was proved by homo-chain and hetero-chain extension polymerization experiment to get the poly (n-Butyl Acrylate) (Mn 17902) and poly (n-Butyl Acrylate)-b-poly(N-Vinyl Pyrrolidone) di-block copolymer (Mn 16029) respectively. Resulting polymers were characterized by 1H NMR, FTIR, GPC, TGA-DTA, DTG, DSC. The kinetic investigations confirmed the pseudo-first-order kinetic of the homopolymerization and linear evolution of the molar mass w.r.t. conversion within the range of polydispersity (PDI) (1.11 –1.20) in dry 1, 4-dioxane medium. The cyto-toxicities of PBA Macro CTA and PBA-b-PNVP polymers were evaluated on RAW264.7 mouse macrophage cells. The cellular viability was found to be 60.31% and 77.83% at 250 μM concentration, respectively for the two polymers. The viability was found more at high concentrations of polymers. The mechanism of cell death associated with these polymers was further evaluated in terms of apoptosis and necrosis on MCF-7 cell lines. Both the polymers induced apoptotic-like changes in MCF-7 cells. © 2019 Elsevier Ltd
The Graft Copolymerization of N-(Hydroxymethyl) Acrylamide onto Xanthan Gum and Its Anti-Oxidative Property
(Pleiades Publishing, 2019) Ashok Kumar; Deepak; Rajesh Kumar; Anand Kumar Keshari; Ragini Srivastava
Abstract: The graft copolymers of N-(hydroxymethyl) acrylamide were synthesized by radical grafting of N‑(hydroxymethyl) acrylamide onto the xanthan gum as a substrate. On increasing the concentration of N‑(hydroxymethyl) acrylamide the grafting parameters decreased gradually, whereas the similar parameters for homopolymer increased. The antioxidant activity of the graft copolymer was 5% less than for xanthan gum and 17% less than for butylated hydroxytoluene. The hydrogen peroxide scavenging activity of graft copolymer was 31 and 15% higher than that of xanthan gum and butylated hydroxytoluene, respectively. The hydroxyl radical scavenging activity of graft copolymer was 15% less than gum and 16% more than butylated hydroxytoluene. The superoxide scavenging activity of graft copolymer was 11% less than that of xanthan gum and 24% more than that of butylated hydroxytoluene. © 2019, Pleiades Publishing, Ltd.
Urinary tract infections in elderly
(2002) I.S. Gambhir; R.K. Singh; Deepak
Urinary tract infections (UTI) are common in elderly. It may manifest in a variety of presentations and needs high index of suspicion. All UTI in elderly men should be assumed to be complicated and functional or anatomic abnormality should be searched for. Catheter related UTI is the most common cause of nosocomial infection, urosepsis is quite common and results in high mortality. Pyuria in elderly may be nonspecific and urine culture may be polymicrobial. Antibiotic treatment shall take into account host factors like renal function, common ADRs, drug interactions, and compliance.