Browsing by Author "Dharmendra Singh"

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A brief review on Ce and Zr-based phase-separated metallic glasses
(Springer, 2025) Devinder Singh; Dharmendra Singh; Radhey Shyam Tiwari; Parthiban Ramasamy; Juergen H. Eckert
Phase-separated metallic glasses (MGs) have attracted a lot of interest recently because they offer a unique opportunity to design composites or alloys with hierarchical microstructure at various length scales. Phase-separated MGs differ from other MGs in terms of their structure and physical properties. Though a lot of theoretical work has been done, there is still a lack of understanding regarding the mechanism underlying phase separation in MGs. In general, phase separation in many MG systems is explained on the basis of nucleation and growth or spinodal decomposition mechanisms. On the other hand, the phase separation in Ce-based MGs is examined based on changes in the electronic structure of Ce atoms. This opens up a new direction of research for delineating issues pertaining to phase separation in amorphous systems. The present brief review aims to provide a comprehensive overview of the phase separation phenomenon in Ce- and Zr-based MG systems. It is broadly divided into two sections: the first section gives a brief introduction into the phase separation in MG systems, mechanisms of phase separation, micro-structural and thermal characteristics, and advantages of phase separation. The second section discusses some of the recent work on Ce- and Zr-based phase-separated MGs with respect to their design and properties. © The Author(s) 2024.
A case report of tinea nigra from North India
(2009) Ragini Tilak; Sanjay Singh; Pradyot Prakash; Dharmendra Singh; Anil Gulati
[No abstract available]
Compositional dependence of glass-forming ability, mechanical and magnetic properties of Ce-Ni-Al (Ga) alloys
(Elsevier Ltd, 2024) Dharmendra Singh; Devinder Singh; Radhey Shyam Tiwari; Rajiv Kumar Mandal; Parthiban Ramasamy; Jürgen Eckert
The glass-forming ability, mechanical and magnetic properties of Ce60Ni25Al15-xGax (x=0, 4, 8 and 15) melt-spun alloys have been investigated. All the alloys show the formation of glassy phase. The supercooled liquid region increases with increase in Ga addition and becomes maximum for x=15 indicating its better glass-forming ability for this composition. A new metallic glass (MG) composition Ce60Ni25Ga15 has been found upon complete substitution of Al by Ga. The mechanical behavior of these alloys has been studied by determining various indentation parameters such as micro-hardness, yield strength and Meyer's exponent. The microhardness property of the Ce-Ni-Al alloy is improved by the addition of Ga. The difference in the formation of shear bands for x=0 and 15 alloys are discussed by estimating the pile-up parameter. The magnetization (M-H) curves of all the samples at 5 K show paramagnetic characteristics with no magnetic hysteresis. The findings reveal that the concentration of Ga has a significant impact on the properties of these alloys. © 2024 Elsevier B.V.
CRITICAL ANALYSIS OF MACHINE LEARNING APPROACHES FOR VEGETATION FRACTIONAL COVER ESTIMATION USING DRONE AND SENTINEL-2 DATA
(Institute of Electrical and Electronics Engineers Inc., 2021) Ajay Kumar Maurya; Maryam Nadeem; Dharmendra Singh; K.P. Singh; N.S. Rajput
The accuracy of estimated fractional vegetation cover (FVC) depends on selecting the best suitable input features, precise ground information, and a prediction model. Therefore, in this paper, four machine learning (ML) algorithms, namely Support Vector Regression (SVR), Random Forest Regression (RFR), K-Nearest Neighbors (KNN), and Linear Regression (LR), are used for FVC estimation using different vegetation indices (VI) as input features. Estimated FVC is compared with the ground truth FVC, which has been calculated with the high-resolution drone images, and their R-square values are calculated. R-square value is used for the assessment of the best input features and model. RFR and KNN emerge as the best suitable ML models in comparison to SVR and LR. The obtained R-square values for the RFR model with the input features used as NDVI, PAVI, SAVI, and MSAVI are 0.873, 0.869, 0.869, and 0.862, respectively. NDVI, PAVI, SAVI, and MSAVI perform better in comparison to other features. Hence, they are permuted together and used as input features, and their results on all the algorithms are moderately better. The highest R-square value obtained is 0.878 when SAVI and PAVI are used as input features for the RFR model. © 2021 IEEE
Crystallization behavior and mechanical properties of (Al90Fe5Ce5)100−xTixamorphous alloys
(Elsevier Ltd, 2016) Dharmendra Singh; Devinder Singh; R.K. Mandal; O.N. Srivastava; R.S. Tiwari
The crystallization behavior and mechanical properties of melt-spun (Al90Fe5Ce5)100−xTix(x = 0, 4, 8 and 12 at.%) alloys have been investigated. The amorphous phase seems to be stable up to x = 8. The crystallization products for the amorphous alloys with x = 0–8 mainly composed of fcc-Al and icosahedral phases in the glassy matrix. The load dependent hardness behavior of amorphous alloys with and without Ti addition has been studied. The hardness value of the amorphous alloys has been found to be 3.72 and 3.07 GPa for x = 0 and 8 at 100 g load respectively. The annealed ribbons have higher hardness and strength as compared to that of as-synthesized ribbons. The enhanced values of hardness of the (Al90Fe5Ce5)100−xTix(x = 0, 4 and 8) alloys are attributed to the combined effects of icosahedral nanoparticles and Al nanoparticles in amorphous matrix. The absence of cracks around the indentation area up to 500 g of load for amorphous alloys suggests better capability to resist crack propagation in comparison to the annealed alloys. The formation of shear bands around the indentation periphery has been observed. The number of visible shear bands for the as-synthesized ribbons is higher in comparison to those of annealed ribbons. The values of yield strength and Meyer exponent of these alloys are also compared. © 2016 Elsevier B.V.
Effect of annealing on the devitrification behavior and mechanical properties of rapidly quenched Ce-based glassy alloys
(Elsevier B.V., 2016) Dharmendra Singh; Devinder Singh; R.K. Mandal; O.N. Srivastava; R.S. Tiwari
This study deals with the effect of controlled crystallization of melt spun Ce75Al25 − xGax (x = 0, 2, 4 and 6 at.%) and Ce60Cu25Al15 − xGax (x = 0, 1, 2 and 4 at.%) metallic glasses on the formation of nano-composites. It has been found that the substitution of Ga significantly affects the devitrification behavior of these alloys. The Ce75Al25 − xGax alloys with x = 0 shows the formation of hexagonal phase (AlCe3 type) while the alloys with x ≥ 2 give rise to the formation of tetragonal phase (Al2CeGa2 type). Contrary to this, for the Ce60Cu25Al15 − xGax alloys, hexagonal phase of AlCeCu type for x = 0 transforms to hexagonal phase of Al2Cu3Ce type for x ≥ 1. The indentation behavior of nano-composites permitted us to understand the nature of microhardness, yield strength and strain hardening constant. They are compared for the above two alloy systems. The load dependent hardness values of annealed ribbons of Ce75Al19Ga6 and Ce60Cu25Al13Ga2 alloys have been found to be ~ 2.80 GPa and ~ 2.96 GPa, respectively. The absence of cracks around the indentation area up to 200 g of load for Ce60Cu25Al15 − xGax alloys suggests better capability to resist crack propagation in comparison to Ce75Al25 − xGax alloys. Latter display cracks at 200 g load. The formation of shear bands around the periphery of the indenter has been observed. The number of visible shear bands in a given area for the Ce75Al25 − xGax alloys is higher in comparison to those of Ce60Cu25Al15 − xGax alloys. The values of yield strength and Meyer exponent of these alloys are also compared. © 2016 Elsevier B.V.
Effect of Ga substitution on low temperature transport and magnetic response of Ce75Al25 metallic glass
(American Institute of Physics Inc., 2018) Devinder Singh; R.S. Tiwari; Dharmendra Singh
The low temperature transport and magnetic behavior of Ce75Al25-xGax (x=0, 2, 4 and 6 at. %) metallic glasses (MGs) have been investigated. The temperature dependence of the resistance shows that the temperature coefficient of resistance (TCR) changes with Ga content. The significant change in the magnetoresistance (MR) behaviour has been observed for these alloys. The alloys with x=2, 4 and 6 show a magnetic field tuned MR transition from positive to negative values at low temperature. The magnetization (M-H) curves of the MGs at 5 K exhibit no magnetic hysteresis and show paramagnetic characteristics. However, a curious type of hysteretic behaviour for Ce75Al25-xGax alloys in non-zero magnetic field has been observed. The hysteric field range has been found to shift to higher magnetic field with increase in the value of x. It has been suggested that the formation of nano-amorphous domains in the glassy matrix and the delocalization of 4f1 configuration of Ce atoms due to Ga substitution may result in the unusual transport behaviour of Ce-Al (Ga) MGs. These changes in the transport behaviour at low temperature have been discussed in terms of the competition between the Kondo effect and Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction. The genesis of hysteretic behaviour in M-H curve has been proposed to arise due to Anti-ferromagnetic screening interaction (AFSI) in two kinds of clusters. © 2018 Author(s).
Effect of quenching rate on the microstructure and mechanical behavior of Ce75Al21Ga4 glassy alloy
(Elsevier Inc., 2017) Dharmendra Singh; Devinder Singh; R.K. Mandal; O.N. Srivastava; R.S. Tiwari
The present study deals with the structural and microstructural changes with respect to the quenching rate and their correlation with mechanical behavior of melt-spun Ce75Al21Ga4 glassy alloys. The ribbons of the alloy have been synthesized at different quenching rates obtained through different wheel speeds (44, 36, 29, 22 and 15 m/s). The glass forming indicators and mechanical properties have been investigated at different quenching rates. The higher quenching rate obtained through high wheel speed (44, 36 and 29 m/s) has led to phase separation giving rise to nano-amorphous domains in a glassy matrix while the lower quenching rate obtained through lower wheel speed (22 and 15 m/s) produces nano-crystalline grains with size ranges from 25 ± 1 to 120 ± 1 nm. It has been found that the size of the nano-amorphous domains decreases with decrease in wheel speed. The mechanical behavior has been studied using micro-indentation technique. The indentation test indicates that with the same chemical composition, the ribbons synthesized at slow quenching rate exhibits higher hardness and yield strength than those synthesized at faster quenching rate. The ribbons synthesized at 44 m/s contains the large free volume and has the highest shear band density. © 2017 Elsevier Inc.
Formation of nano-amorphous domains in Ce75Al25 - XGax alloys with delocalization of cerium 4f electrons
(Elsevier Ltd, 2015) Dharmendra Singh; Sohini Basu; R.K. Mandal; O.N. Srivastava; R.S. Tiwari
The formation of nano-amorphous domains in melt spun ribbons of Ce75Al25 - xGax alloys with x = 0, 0.01, 0.1, 0.5 and 1 is reported. For x = 0, a homogenous metallic glass feature is observed. Ga substitution has led to phase separation giving rise to nano-amorphous domains in a glassy matrix. The rationale of phase separation could not be explained in terms of enthalpy of mixing of the three possible binaries in this system. The Ce L3-edge XAS spectra of melt-spun ribbons for x = 0, 0.5 and 4 have shown appearance of 4f0 delocalized states in Ga substituted alloy. Such a substitution has led to shortening of Ce-Ce distance in the alloys owing to chemical pressure. This work, therefore, opens up new direction of research for delineating issues pertaining to phase separation in amorphous systems. © 2015 Elsevier Ltd. All rights reserved.
Glass forming ability, thermal stability and indentation characteristics of Ce60Cu25Al15 - xGax (0 ≤ x ≤ 4) metallic glasses
(Elsevier B.V., 2015) Dharmendra Singh; R.K. Mandal; O.N. Srivastava; R.S. Tiwari
Abstract Glass forming ability, thermal stability and indentation characteristics of Ce60Cu25Al15 - xGax (0 ≤ x ≤ 4) metallic glasses have been investigated. Amorphous phase has been confirmed in all these samples with the help of X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) studies. The compositional dependence of the glass forming ability (GFA) and its correlation with related parameters as well as thermal stability have also been discussed. The load dependent hardness behavior of metallic glasses is reported in detail. It has been observed that substitution of 1 at.% Ga improved micro-hardness property of Ce-Cu-Al-Ga alloy. The value of yield strength of the materials is estimated with the help of hardness data and Meyer exponent. It has been found that this exponent decreases with respect to Ga substitution. © 2015 Elsevier B.V.
Glass forming ability, thermal stability and indentation characteristics of Ce75Al25-xGax metallic glasses
(2014) Dharmendra Singh; Devinder Singh; R.K. Mandal; O.N. Srivastava; R.S. Tiwari
The glass forming ability and indentation characteristics of melt-spun Ce75Al25-xGax (x = 0, 2, 4 and 6 at.%) metallic glasses have been investigated. The substitution of Ga decreases the glass transition temperature (Tg), while increases the supercooled liquid region (ΔTx). The small amount of Ga substitution has led to appearance of second diffuse halos in the X-ray diffraction (XRD) pattern. The observation of "bi-amorphous phases" is thus asserted. The transmission electron microscopic images led us to conclude the formation of nano-amorphous domains after Ga substitution. The load dependent hardness behavior of metallic glasses with and without Ga substitution has been studied. The substitution of Ga improves the microhardness property of Ce-Al alloy. The formation of shear bands around the indentation periphery has been observed. The value of yield strength and Meyer exponent of these alloys has been compared. © 2013 Elsevier B.V. All rights reserved.
Glycine betaine modulates chromium (VI)-induced morpho-physiological and biochemical responses to mitigate chromium toxicity in chickpea (Cicer arietinum L.) cultivars
(Nature Research, 2022) Deepti Singh; Chandan Kumar Singh; Dharmendra Singh; Susheel Kumar Sarkar; Saroj Kumar Prasad; Nathi Lal Sharma; Ishwar Singh
Chromium (Cr) accumulation in crops reduces yield. Here, we grew two chickpea cultivars, Pusa 2085 (Cr-tolerant) and Pusa Green 112 (Cr-sensitive), in hydroponic and pot conditions under different Cr treatments: 0 and 120 µM Cr and 120 µM Cr + 100 mM glycine betaine (GB). For plants grown in the hydroponic media, we evaluated root morphological attributes and plasma membrane integrity via Evans blue uptake. We also estimated H+-ATPase activity in the roots and leaves of both cultivars. Plants in pots under conditions similar to those of the hydroponic setup were used to measure growth traits, oxidative stress, chlorophyll contents, enzymatic activities, proline levels, and nutrient elements at the seedling stage. Traits such as Cr uptake in different plant parts after 42 days and grain yield after 140 days of growth were also evaluated. In both cultivars, plant growth traits, chlorophyll contents, enzymatic activities, nutrient contents, and grain yield were significantly reduced under Cr stress, whereas oxidative stress and proline levels were increased compared to the control levels. Further, Cr uptake was remarkably decreased in the roots and leaves of Cr-tolerant than in Cr-sensitive cultivars. Application of GB led to improved root growth and morpho-physiological attributes and reduced oxidative stress along with reduced loss in plasma membrane integrity and subsequently increase in H+-ATPase activity. An increment in these parameters shows that the exogenous application of GB improves the Cr stress tolerance in chickpea plants. © 2022, The Author(s).
Hydrogen Sulfide and Silicon Together Alleviate Chromium (VI) Toxicity by Modulating Morpho-Physiological and Key Antioxidant Defense Systems in Chickpea (Cicer arietinum L.) Varieties
(Frontiers Media S.A., 2022) Deepti Singh; Chandan Kumar Singh; Manzer H. Siddiqui; Saud Alamri; Susheel Kumar Sarkar; Abhishek Rathore; Saroj Kumar Prasad; Dharmendra Singh; Nathi Lal Sharma; Hazem M. Kalaji; Adam Brysiewicz
Extensive use of chromium (Cr) in anthropogenic activities leads to Cr toxicity in plants causing serious threat to the environment. Cr toxicity impairs plant growth, development, and metabolism. In the present study, we explored the effect of NaHS [a hydrogen sulfide; (H2S), donor] and silicon (Si), alone or in combination, on two chickpea (Cicer arietinum) varieties (Pusa 2085 and Pusa Green 112), in pot conditions under Cr stress. Cr stress increased accumulation of Cr reduction of the plasma membrane (PM) H+-ATPase activity and decreased in photosynthetic pigments, essential minerals, relative water contents (RWC), and enzymatic and non-enzymatic antioxidants in both the varieties. Exogenous application of NaHS and Si on plants exposed to Cr stress mitigated the effect of Cr and enhanced the physiological and biochemical parameters by reducing Cr accumulation and oxidative stress in roots and leaves. The interactive effects of NaHS and Si showed a highly significant and positive correlation with PM H+-ATPase activity, photosynthetic pigments, essential minerals, RWC, proline content, and enzymatic antioxidant activities (catalase, peroxidase, ascorbate peroxidase, dehydroascorbate reductase, superoxide dismutase, and monodehydroascorbate reductase). A similar trend was observed for non-enzymatic antioxidant activities (ascorbic acid, glutathione, oxidized glutathione, and dehydroascorbic acid level) in leaves while oxidative damage in roots and leaves showed a negative correlation. Exogenous application of NaHS + Si could enhance Cr stress tolerance in chickpea and field studies are warranted for assessing crop yield under Cr-affected area. Copyright © 2022 Singh, Singh, Siddiqui, Alamri, Sarkar, Rathore, Prasad, Singh, Sharma, Kalaji and Brysiewicz.
Influence of Ga substitution on the nature of glasses in Zr69.5Al7.5-xGaxCu12Ni11 and Ce75Al25-xGax metallic glass compositions
(Materials Research Society, 2015) R.K. Mandai; R.S. Tiwari; Devinder Singh; Dharmendra Singh
In this presentation, results of our recent investigations on the role of Ga on Al site in Zr69.5Al75.xGaxCu12Ni11 and Ce75Al25-xGax metallic glass compositions will be discussed. Ga like Al is normally expected to be in trivalent state. However, it may go in monovalent state depending on other alloying elements. The rapidly solidified melt spun ribbons of above two alloys gave rise to two important conclusions. The Zr69.5Al75-xGaxCu12Ni11 system displayed metallic glass formation in the range of x=0 to 7.5. In this process, we have come out with a new composition of glass without Al corresponding to x=7.5. In contrast to the above, for Ce-Al(Ga) system, we have observed phase separation in glass after dilute substitution of Ga. It seems that such a phase separation in this system cannot be understood in terms of summation of enthalpy of mixing of the various possible binaries in this system. The substitution of Ga in different valence states might have created chemical pressure leading to creation of two types of distinct major clusters. The phase separation may be due to this. This has also given rise to excursion of Ce 4f-states of the alloy. This and aforesaid 'chemical pressure' will be corroborated based on results of binary Ce-Al system under pressure by other investigators. © 2015 Materials Research Society.
Microstructural effect on the low temperature transport properties of Ce-Al (Ga) metallic glasses
(Elsevier Ltd, 2016) Dharmendra Singh; Devinder Singh; O.N. Srivastava; R.S. Tiwari
The substitution of Ga in Ce75Al25-xGax (x = 0 and 4 at.%) metallic glasses (MGs) has led to phase separation giving rise to nano-amorphous domains in a glassy matrix. The CeL3-edge XAS spectra for x = 4 has shown appearance of 4f0 delocalized states. The temperature coefficient of resistance (TCR) becomes higher with addition of Ga. The magnetic field tuned magnetoresistance (MR) transition from positive to negative values has been observed for the first time with Ga substitution. These changes in the transport properties have been discussed in terms of formation of nano-amorphous domains and its link with 4f electrons for Ce atoms. © 2016 Elsevier Ltd. All rights reserved.
Protocatechuic Acid and its Derivatives: Synthesis, Antioxidant Properties, and Potential In Vivo Wound Healing Applications
(John Wiley and Sons Ltd, 2025) Sumit Maurya; Sumit Manna; Mala Singh; Dharmendra Singh; Malay Nayak; Sudip Mukherjee; Arun Kumar Manna
Treatment of chronic wounds is a potential healthcare problem, affecting people globally. Traditional methods of wound healing are prone to several limitations, like infections, oxidative stress, and development of secondary wounds. Management of oxidative stress is an interesting platform to deal with chronic wounds. For this study, novel derivatives of protocatechuic acid, a naturally occurring phenolic acid, were designed by modifying the carboxylic acid moiety while preserving the hydroxyl groups for radical scavenging. So, a series of amide conjugates were synthesized by incorporating various amine moieties. Glucose conjugates were obtained through both click chemistry and direct coupling strategies and a chlorinated derivative was also prepared. The antioxidant potential of the compounds was screened using DPPH assay, followed by in vitro DCFDA assay on HEK-293T cell line. Top 5 lead molecules were checked for biocompatibility through MTT assay, which provided us with top 2 leads, Compounds 12 and 17 which were examined for a wound healing study on Wistar rats along with the starting compound 1. It was observed that Compound 17 demonstrated excellent wound tissue regeneration on day 12, as compared to the control group, suggesting the promising role of triazole and glucose moieties conjugation for relieving oxidative stress and wound management. © 2025 Wiley-VCH GmbH.
Synthesis and Indentation Behavior of Amorphous and Nanocrystalline Phases in Rapidly Quenched Cu-Ga-Mg-Ti and Cu-Al-Mg-Ti Alloys
(2013) Devinder Singh; Dharmendra Singh; T.P. Yadav; R.K. Mandal; R.S. Tiwari; O.N. Srivastava
Rapidly solidified ribbons of Cu-Ga-Mg-Ti and Cu-Al-Mg-Ti alloys show the formation of γ-brass type phase, which is an approximant of quasicrystals. The Cu-Ga-Mg-Ti alloy displays ordered γ-brass structure, whereas Cu-Al-Mg-Ti leads to the formation of amorphous and nanocrystalline disordered bcc γ-brass phase. The hardness values of as-synthesized ribbons of Cu-Ga-Mg-Ti and Cu-Al-Mg-Ti alloys are ~7.36 and ~9.01 GPa, respectively. The high hardness value of the Cu-Al-Mg-Ti alloy can be attributed to the combined effects of amorphous and nanocrystalline phases. The absence of cracks around the indentation up to 100 g of load of this alloy suggests better toughness in comparison with Cu-Ga-Mg-Ti alloy. The formation of shear bands is more prominent in case of Cu-Al-Mg-Ti alloy. The value of yield strength and Meyer exponent of the material has been estimated. It has been found that the indentation parameter seems to be sensitive to structural and microstructural variations. © 2013 Springer Science+Business Media New York and ASM International.
The rK39 strip test is non-predictor of clinical status for kala-azar
(2009) Dharmendra Singh; Shyam Sundar; Tribhuban Mohapatra
Background. The rK39 strip test is reported to be simple, sensitive, specific, non-invasive and economical test. Since this method is supposed to be patient friendly, it may easily be accepted for sero-epidemiological surveys. An attempt was made to evaluate the role of rK39 strip test in pre and post treatment phases of Kala azar, as a diagnostic and prognostic marker, in addition to other laboratory investigations, in order to evaluate its role in sero-epidemiological surveys. Findings. A total of 210 cases were selected for the study. One hundred clinically and parasitologically confirmed cases were corroborated with other hematological profiles. The formol-gel test was included along with well matched control group comprising of normal endemic controls (50), non-endemic normals (20) and other febrile cases (40). All groups were tested by rK39 strip test. Fifty Kala azar cases were followed up after completion of successful treatment. They were subjected to rK39 strip test after 0, 90 and 180 days of completion of successful treatment. The rK39 showed sensitivity, specificity, PPV, NPV, and diagnostic accuracy of 98% (95% CI 91.7-100), 100%, 100%, 90% (95% CI 66-100) and 98% (95% CI 92.6-100) respectively. All the 50 cured followed up cases showed positive result by rK39 strip test even after 180 days of completion of successful treatment. Conclusion. The test seems an ideal qualitative test for the diagnosis of kala-azar. But for sero-epidemiological studies the test may be used with other parameters. Alternatively a quantitative ELISA using rK39 antigen may be used. © 2009 Singh et al; licensee BioMed Central Ltd.
Validation of SYBR green I based closed tube loop mediated isothermal amplification (LAMP) assay and simplified direct-blood-lysis (DBL)-LAMP assay for diagnosis of visceral leishmaniasis (VL)
(Public Library of Science, 2018) Keerti Kaumudee Dixit; Sandeep Verma; Om Prakash Singh; Dharmendra Singh; Akhil Pratap Singh; Ratan Gupta; Narendra Singh Negi; Pradeep Das; Shyam Sundar; Ruchi Singh; Poonam Salotra
Background: The World Health Organization has targeted elimination of visceral leishmaniasis (VL) in the Indian subcontinent (ISC) by 2020. Despite distinctive decline seen in the number of VL cases in ISC, there is still a quest for development of a diagnostic test which has the utility for detection of active infection and relapse cases and as a test of cure. The present study validated the sensitivity and specificity of SYBR Green I based closed tube LAMP assay reported by us for diagnosis of VL. Methodology: The validation study was carried out at two endemic sites in India, located at Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Patna and Institute of Medical Sciences (IMS), Banaras Hindu University (BHU), Varanasi. Standard operating protocols were provided at the two sites for applying LAMP assay on confirmed VL cases. The diagnostic accuracy of LAMP assay was evaluated by Receiver operator curve (ROC) analysis. Furthermore, a simplified LAMP assay based on direct blood lysis, DBL-LAMP, was developed and verified for its diagnostic accuracy. Principal findings: A total of 267 eligible participants were included in the study which comprised of 179 VL cases and 88 controls. Sensitivity and specificity of the LAMP assay were 98.32% (95% C.I– 95.2–99.7%) and 96.59% (95% C.I.-90.4–99.3%), respectively. ROC curve analysis depicted no significant difference between area under curve (AUC ROC ) for LAMP assay and rK39 RDT, indicative of LAMP as an excellent diagnostic test. DBL-LAMP assay, performed on 67 VL and 100 control samples, yielded a sensitivity of 93.05% (95% C.I- 84.75–97%) and specificity of 100% (95% C.I.- 96.30–100%). Conclusions/Significance: The validated closed tube LAMP for diagnosis of VL will provide impetus to the ongoing VL elimination programme in ISC. The assay based on direct blood lysis promotes its scope for application in field settings by further reducing time and cost. © 2018 Dixit et al. http://creativecommons.org/licenses/by/4.0/.
Zinc oxide nanoparticles alleviate chromium-induced oxidative stress by modulating physio-biochemical aspects and organic acids in chickpea (Cicer arietinum L.)
(Elsevier Masson s.r.l., 2024) Deepti Singh; Nathi Lal Sharma; Dharmendra Singh; Manzer H. Siddiqui; Susheel Kumar Sarkar; Abhishek Rathore; Saroj Kumar Prasad; Abdel-Rhman Z. Gaafar; Sadam Hussain
Extensive chromium (Cr) release into water and soil severely impairs crop productivity worldwide. Nanoparticle (NP) technology has shown potential for reducing heavy metal toxicity and improving plant physicochemical profiles. Herein, we investigated the effects of exogenous zinc oxide NPs (ZnO-NPs) on alleviating Cr stress in Cr-sensitive and tolerant chickpea genotypes. Hydroponically grown chickpea plants were exposed to Cr stress (0 and 120 μM) and ZnO-NPs (25 μM, 20 nm size) twice at a 7-day interval. Cr exposure reduced physiochemical profiles, ion content, cell viability, and gas exchange parameters, and it increased organic acid exudate accumulation in roots and the Cr content in the roots and leaves of the plants. However, ZnO-NP application significantly increased plant growth, enzymatic activities, proline, total soluble sugar, and protein and gas exchange parameters and reduced malondialdehyde and hydrogen peroxide levels, Cr content in roots, and organic acid presence to improve root cell viability. This study provides new insights into the role of ZnO-NPs in reducing oxidative stress along with Cr accumulation and mobility due to low levels of organic acids in chickpea roots. Notably, the Cr-tolerant genotype exhibited more pronounced alleviation of Cr stress by ZnO-NPs. These findings highlight the potential of ZnO-NP in regulating plant growth, reducing Cr accumulation, and promoting sustainable agricultural development. © 2023 Elsevier Masson SAS