Browsing by Author "Saumya Singh"

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2-Boronobenzoic acid functionalized silver nanocubes for label free detection of l-arginine and l-cysteine with real sample applications
(Royal Society of Chemistry, 2024) Saumya Singh; K.K. Upadhyay
We report hereby a sensitive and rapid label free colorimetric assay of two amino acids, viz.l-arginine (l-Arg) and l-cysteine (l-Cys), through silver sol synthesized via a wet chemical method using 2-boronobenzoic acid (2- BBA) as a reducing and capping reagent in an aqueous alkaline medium. 2-BBA was synthesized in situ by the reaction of 2-formylphenylboronic acid (2-FBPA) and silver nitrate through Tollen's method. The as-synthesized silver sol exhibited the formation of nanocubes having their most predominant size in the range of 20-25 nm upon their TEM scanning and exhibiting an SPR band at 401 nm in their UV-vis spectrum. The same were further characterized by SEM, EDX, AFM, FTIR, XPS, DLS, and zeta potential measurements also. Separate interaction of the two amino acids, viz., l-Arg and l-Cys, with diluted AgNCs (1 : 2; AgNCs and Millipore water V/V) exhibited two different colors, pinkish grey and blue, respectively accompanied by distinctive shifts in their surface plasmon resonance (SPR) band also. The detection limits were found to be 6 μM and 3 μM for l-Arg and l-Cys respectively. Furthermore, l-Arg and l-Cys were quantified in a pharmaceutical sample each with their respective recovery rates of 99.2% and 90.1%. These AgNCs exhibited rich SERS characteristics also by intensifying the Raman peaks of l-Arg and l-Cys. Only a few one-pot aqueous chemical syntheses of silver nanocubes have been reported previously. Most probably, this is the third report of its kind. To the best of our knowledge, no silver nanoprobe exhibiting simultaneous detection of l-Arg and l-Cys has been reported to date. © 2024 The Royal Society of Chemistry.
5-Amino uracil activated silver nano resonators for highly selective visual detection of dopamine and as an agonist towards BAP: Promoting shoot growth in Bacopa monnieri L.
(Elsevier B.V., 2024) Saumya Singh; Raksha Singh; Anurag Kumar Singh; Minu Yadav; S.K. Mishra; Jyoti Dixit; Pooja Verma; K.N. Tiwari; K.K. Upadhyay
Silver nanoparticles (AgNPs) with an average size of about 17.5 nm have been synthesized using 5-amino uracil as a reducing and capping agent. The concentration of these AgNPs was worked out to be 48 nM. These AgNPs served as a highly selective optical sensor against an important neurotransmitter like dopamine (DA) at its nano molar level (94 nM) with the linearity range of 1–5 µM. The quantification of DA in one of its injection sample was also achieved with a recovery of 91 %. Studies like FTIR, UV–Vis, XPS, SEM, TEM, EDX, DLS and Zeta potential measurements have supported our findings. Significant amplification in the Raman signal of DA was also observed upon its addition into as prepared AgNPs solution. Moreover, these AgNPs seemed to augment the activity of cytokinin (BAP) in synergistic fashion and enhanced in vitro high frequency shoots regeneration in B. monnieri L. and also led to increment in its antioxidant metabolite contents like phenol and flavonoid. © 2023 Elsevier B.V.
A multifunctional coumarin-based probe for distinguishable detection of Cu2+ and Zn2+: its piezochromic, viscochromic and AIE behavior with real sample analysis and bio-imaging applications
(Royal Society of Chemistry, 2023) Aayoosh Singh; Pranjalee Yadav; Saumya Singh; Pradeep Kumar; S. Srikrishna; Vinod P. Singh
A multifunctional coumarin based organic luminophore, CTH, has been synthesized and its fluorescence properties are investigated. The probe displays the properties of aggregation-induced emission (AIE), viscochromism, piezochromism and distinguishable flourometric sensing of Cu2+ and Zn2+ ions. The molecular structure of the probe has been determined by FT-IR, UV-Vis, NMR, and HRMS spectral studies. Powder XRD, dynamic light scattering (DLS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and density functional theory (DFT) calculations have been carried out to explore the photo-physical properties of the synthesized probe. CTH is non-emissive in ethanol, but upon adding water its emission intensity increases by 8-fold and fluorescence quantum yield increases from Φ = 1.19 × 10−3 (fw = 70%) to Φ= 8.50 × 10−3 (fw = 99%), indicating typical AIE behaviour. The probe demonstrates excellent viscochromism with increasing glycerol fraction in EtOH. Upon grinding, the probe exhibits piezochromic properties and shows an emissive color change from blue to bright green along with a bathochromic shift of 83 nm. In addition to the aforementioned properties, the probe selectively discriminates Cu2+ and Zn2+ from a pool of different metal ions in DMF : H2O (3 : 7, v/v, pH 7.4) HEPES buffer. CTH detects Cu2+ and Zn2+ ions via paramagnetic fluorescence quenching and CHEF induced fluorescence enhancement, respectively. Job's plots suggest 1 : 1 binding stoichiometry for both CTH-Cu2+ and CTH-Zn2+ complexes. Significant low detection limits (LODs) of 6.75 nM for Cu2+ and 2.97 nM for Zn2+ have been observed and molecular logic gates have also been constructed. The probe has been effectively utilized in the bio-imaging of Cu2+ and Zn2+ in the gut tissue of Drosophila and in the quantification of Cu2+ and Zn2+ in real water samples. © 2023 The Royal Society of Chemistry.
ACUTE TOXICITY OF 4-OCTYLPHENOL ON THE HISTOPATHOLOGICAL CHANGES OF OVARY IN THE FRESHWATER STINGING CATFISH HETEROPNEUSTES FOSSILIS
(Prof (Dr.) P. R. Yadav, 2025) Ashvani Kumar Srivastav; Saumya Singh; Radha Chaube
4-Octylphenol (4-OP) is a degradation product of alkylphenol polyethoxylates (APEs).APEs represent an important class of non-ionic surfactants widely used in many pesticide formulations, oil paint formulations, detergent formulations and plastic products for industrial and domestic use. The 96 hrs LC50 value of 4-Octylphenol was 0.9 mg/L for the fish Heteropneustes fossilis. Mortality of fish was recorded for each of the concentrations during exposure period and used for the estimation of LC50 value. Therefore 1/10th and 1/50th of the LC50 value i.e., 0.9 mg/Lwas used for the experimental study. For 4-octylphenol two doses were decided, i.e., high dose (0.09 mg/L) and low dose (0.018 mg/L).After exposure to these doses behavior and histopathology changes were determined after 1 and 7 days. In the present study, ovary-somatic index (OSI) decreased significantly in a duration and dose dependent manner. Further considering behavioral changes catfish showed frequent jumping, decreased opercular movement and resting time, erratic movement, secretion of excess mucous from the body and increased air gulping activities. Histopathological changes in ovary tissues of Heteropneustes fossilis by hematoxylin-eosin staining showed architectural deformities in oocytes with increase in interfollicular spaces with damaged oocytes and increased in atretic and dead oocytes in comparison to control sections. Shifting and clumping of nucleus with cytoplasm was observed. The changes were duration and dose dependent manner. In conclusion, present study suggests that 4-OP can be a potent toxicant for aquatic organisms and further detailed investigation is required in this area, which is under progress in our laboratory. © 2025, Prof (Dr.) P. R. Yadav. All rights reserved.
Advances in remote sensing in measuring urban heat island effect and its management
(Elsevier, 2023) Saumya Singh; Rajesh Kumar Mall; A. Chaturvedi; Nidhi Singh; Prashant K. Srivastava
The urban environment has undergone rapid change as a result of urbanization and the increase in global temperature, which has affected the energy balance and heat fluxes. The urban heat island (UHI) phenomenon is brought on by these changes in geometry, building materials, land use, and land cover, among other factors, which raise the temperature in cities relative to their rural and suburban surroundings. The microclimate, ecology, air quality, and infrastructure are all significantly impacted by the UHI effect, which also has a significant impact on energy needs. Meteorological data cannot be used to measure the UHI effect due to large spatial heterogeneity and the lack of dense weather station networks. Remote sensing offers an effective way to track, measure, and manage the UHI effect in such circumstances. Thermal remote sensing technology has made it possible to estimate the UHI effect in high spatial and temporal resolution. The effectiveness of the technique in multicity analysis has been reported in several studies, prompting research to advance the techniques. Urban ecosystems can be transformed from unsustainable to sustainable one on a global scale with the development of multispectral to hyperspectral imaging. © 2024 Elsevier Ltd. All rights reserved.
Anthracene appended AIEgen as a reversible fluorescence sensor for hazardous cyanide ion in environmental samples and fabrication of portable test kit for on spot detection
(Elsevier B.V., 2025) Pranjalee Yadav; Aayoosh Singh; Gautam Kumar; Saumya Singh; Vinod Prasad Singh
CN− is a frequently encountered pollutant in water and soil. Due to its extreme lethal effect on mammals, serious consideration and efforts are needed for monitoring this hazardous anion. To address this challenge, herein, an anthracene-appended AIEgen (ACFH) has been synthesized and developed for selective fluorometric detection of CN− ion. The detection limit of the probe has been found to be 3.42 × 10−7 M (8.89 ppb), which is much lower than WHO standard (2.7 × 10−6 M). The interaction with CN− causes deprotonation of the probe and subsequent loss of planarity, which has been thoroughly confirmed from 1H NMR titrations and DFT calculations. The reversibility and reusability of ACFH and corresponding logic gates enhance its sensing performance and efficacy. Notably, it has been utilized to meritoriously quantify CN− in various water samples and the fabrication of a portable test kit for monitoring CN− in real time. In addition, the aggregation induced emission (AIE) property has been precisely explored with the aid of fluorescence spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), fluorescence quantum yield and lifetime analysis. © 2024 Elsevier B.V.
Aroyl hydrazone with large Stokes shift as a fluorescent probe for detection of Cu2+ in pure aqueous medium and in vivo studies
(Elsevier B.V., 2020) Romi Dwivedi; Saumya Singh; Brijesh Singh Chauhan; S. Srikrishna; Anoop Kumar Panday; Lokman H. Choudhury; Vinod Prasad Singh
An aroyl hydrazone based fluorescent probe, hpsh, has been developed for the selective detection of Cu2+ ions in pure aqueous medium by static fluorescence quenching. The fluorescence quenching of hpsh in the presence of Cu2+ takes place as a result of ground state complex formation through intramolecular charge transfer (ICT). Addition of Cu2+ ions changes the color of the solution from colorless to yellow-green which is clearly visible by naked eye. Large Stokes shift of hpsh prevents the self-quenching of the probe in absence of metal ions. The observed stoichiometry between Cu2+ and probe has been found as 1:2 (M: L). MTT assay of hpsh on fruit flies confirms that the probe is non-toxic and biocompatible. The plausible in vivo bioimaging application of the probe to detect Cu2+ in Drosophila gut tissues as well as in adult fruit fly has been investigated with excellent results. © 2020 Elsevier B.V.
Changing spatio-temporal trends of heat wave and severe heat wave events over India: An emerging health hazard
(John Wiley and Sons Ltd, 2021) Saumya Singh; R.K. Mall; Nidhi Singh
Heat wave (HW) and severe heat wave (SHW) events are the manifestations of extreme temperature causing an array of impacts on health, ecosystem, and economy. Since the mid-20th century, an increasing trend in the characteristics of heat waves has been observed over India causing an increased rate in human mortality. Our study aimed to analyse monthly, seasonal, and decadal variations along with long-term trends of HW and SHW events for pre-monsoon (March–May) and early summer monsoon (June–July) season during 1951–2016. HW and SHW events were identified using revised criteria given by the India Meteorological Department (IMD) using daily gridded maximum temperature data at 0.5° × 0.5° resolution from IMD. The study found a Spatio-temporal shift in the occurrence of HW events with a significantly increasing trend in three prominent heat wave prone regions that is northwestern, central, and south-central India, the highest being in West Madhya Pradesh (0.80 events/year), while a significantly decreasing trend was observed over an eastern region that is Gangetic West Bengal (−0.13events/year). SHW events showed a southward expansion and a spatial surge during the decades of 2001–2010 and 2010–2016. Tri-decadal comparative assessment shows a decadal increase of around 12 HW and 5 SHW events post the 1980s. State-wise Pearson's correlation between HW/SHW events and observed mortality reveals that the eastern coastal states that are Odisha and Andhra Pradesh show a significant positive correlation of 0.62 and 0.73, respectively. This significantly increasing trend in HW and SHW events may pose a grave risk to human health, predominantly on the vulnerable sections of the society. Heat waves need to be recognized as a potential health risk and demand further study, robust preparedness, and policy intervention. © 2020 Royal Meteorological Society
Climate Changes over the Indian Subcontinent: Scenarios and Impacts
(Springer Science and Business Media B.V., 2022) R.K. Mall; Nidhi Singh; Subhi Patel; Saumya Singh; Aman Arora; R. Bhatla; R.S. Singh; P.K. Srivastava
It has now been well established that the rise in global mercury has driven climate change phenomena that have led to extreme temperature events, sea level rise, change in the hydrological cycle, frequent droughts and floods, and cyclones and forest fires and caused a myriad of adverse impacts on vital worldwide sectors such as agriculture, water and health. The impact of climate change is anticipated to be more adverse for destitute and socioeconomically deprived populations from developing and underdeveloped nations owing to poor adaptive capacity and higher sensitivity. The present chapter focuses on the Indian context, where it presents shreds of evidence of the impact of climate change in the past, present and future such as extreme events like heat waves, diurnal temperature range, shrinking of Himalayan glaciers, shifting of rainfall patterns, increased susceptibility to floods and droughts, and its impact on some of the important sectors. The chapter shows clear evidence of a decline in crop production and productivity of some of the important crops such as wheat, rice, sugarcane, maize, potato, tomato, etc. The recent studies established an increase in morbidity and mortality associated with extreme temperature and poor air quality associated with increased particulate matter (PM), NOx, SOx, O3, black carbon and other ambient pollutants. In addition, important river basins of India, such as Gomti, Gandak, Vaigai, Mahi, Varuna and Ghaghra, have shown increased susceptibility to flooding and drought events that are more likely to be frequent and severe in the future under different climate change scenarios owing to changes in erratic rainfall patterns and increasing temperature. The chapter also discusses the potential adaptation and mitigation strategies that would help policymakers to combat climate change amid the rising susceptible population. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.
Evaluation of CORDEX- South Asia regional climate models for heat wave simulations over India
(Elsevier Ltd, 2021) Saumya Singh; R.K. Mall; J. Dadich; S. Verma; J.V. Singh; A. Gupta
The episodes of heat wave events have strengthened in recent decades causing great concern for human health, agriculture and natural ecosystem. In the present study, Regional Climate Models (RCMs) namely, CCAM and RegCM, from Coordinated Regional Climate Downscaling Experiments (CORDEX) for South Asia (SA) are evaluated for simulating heat waves (March–June) for a long-term period (1971 to 2005) over India in comparison with observations from India Meteorological Department (IMD). The statistical analysis (correlation, RMSE, MAE, ECDF) results reveal differences in RCMs in simulating spatial pattern and trends of maximum temperature before bias correction. Variance scaling bias correction is found to remove bias and improve model simulations in capturing temperature variability. An increase in correlation in daily observations from 0.24 to 0.70 and reduction in RMSE from 8.08 °C to 2.02 °C and MAE from 3.87 °C to 2.43 °C after bias correction is observed between model and observation. LMDZ4 and GFDL-ESM2M are found to perform best in simulating interannual variability of seasonal mean maximum temperature with an underestimation of −7.74% and −15.41% which improved significantly to around −1.51% and − 0.78%, respectively after bias correction over India. LMDZ4 and GFDL-ESM2M are also best-performing models in significantly reproducing the heat wave frequency and spatial variability in closer proximity with observations over India amongst all models after bias correction. Over NW and western regions, the LMDZ4 and GFDL-ESM2M ensemble models successfully capture the increasing trend of 0.2 events/year and 0.4 events/year accordance to IMD and IITM criteria, respectively. However, the ACCESS1.0, CNRM-CM5 and CCSM4 ensemble experiments overestimated heat waves by ±40 events in most sub-divisions in India. Over the central Indian regions, the ACCESS 1.0 and CNRM-CM5 model output show a negative trend of −0.2 events/year and large spatial variability possibly due to model associated uncertainties. Overall the results show an improvement in capturing maximum temperature and heat waves across the regions of Indian sub-continent in the bias-corrected downscaled CORDEX-SA ensemble RCMs than without bias-corrected output. The study suggests a way forward to assess RCMs performance and uncertainty in extreme weather analysis in future projections. © 2020 Elsevier B.V.
Frequency dominates intensity of future heat waves over India
(Elsevier Inc., 2023) Saumya Singh; R.K. Mall
Future changes in heat wave characteristics over India have been analyzed using Coordinated Regional Climate Downscaling Experiments (CORDEX) for South Asia (SA) regional climate model simulations for mid-term (2041–2060) and long-term (2081–2099) future under the representative concentration pathway (RCP) 4.5 and RCP 8.5 emission scenarios, respectively. SMHI_CSIRO-MK3.6 was found to be the best model in simulating heat wave trend over India for historical period. Future projections show a four-to-seven-fold increase in heat wave frequency for mid-term and long-term future under RCP 4.5 scenario, and five-to-ten-fold increase under RCP 8.5 scenario with increase in frequency dominating intensity in both the scenarios. Northwestern, Central, and South-central India emerged as future heat wave hotspots with largest increase in the south-central region. This high-resolution regional future projection of heat wave occurrence will serve as a baseline for developing transformational heat-resilient policies and adaptation measures to reduce potential impact on human health, agriculture, and infrastructure. © 2023 The Authors
Glucosamine functionalized gold nanoparticles for the specific detection and colorimetric assay of glutathione in real samples
(Royal Society of Chemistry, 2024) Anurag Kumar Singh; Saumya Singh; Raksha Singh; Manish Sharma; Ida Tiwari; K.K. Upadhyay
In this study, we report an experimental protocol based on gold nanoparticles (GNPs) for the selective and efficient chromogenic detection and determination of glutathione in two pharmaceutical samples, viz. Maxiliv and Glutaderm, in real time. The glucosamine hydrochloride driven hydrothermal (40 °C) wet chemical reduction of gold(iii) chloride trihydrate resulted in gold sol with a ruby red color exhibiting a surface plasmon resonance (SPR) at 521 nm. The most frequent average size of these GNPs was found to be 23 nm and their concentration was evaluated to be 8.4 nM. The zeta potential measurements and interaction of these GNPs against NaCl of varying molarities indicated their long-term stability. According to SEM analysis, these GNPs exhibited a nanowire morphology and produced a categorical color change from ruby red to blue selectively with GSH in the presence of a wide range of similar analytes in real time. UV-vis, FT-IR, XPS, SEM, TEM, AFM, EDAX, DLS, zeta potential, and other techniques were used to characterize the as-synthesized GNPs and to study their interaction with glutathione. © 2024 The Royal Society of Chemistry.
How virtuous are the bias corrected CMIP6 models in the simulation of heatwave over different meteorological subdivisions of India?
(Elsevier B.V., 2024) Saumya Singh; R.K. Mall; Praveen K. Singh; R. Bhatla; Pawan K. Chaubey
With rising global temperatures, extreme weather events have become more frequent, intense and of longer duration. CMIP6 GCMs provide improved climate simulations that need robust evaluation for historical period for reliable future projections. The present study assesses the ability of bias corrected CMIP6 14 Global Climate Models (GCMs) in simulating heat wave over India for March–June during the historical period (1951–2014). Heat waves were identified using IITM criteria. Model biases were removed using variance scaling bias correction method that showed higher correlation (0.93) and lower root mean square error (2.15) and improvement in approximating the inter-annual variability as well as spatial patterns as observed maximum temperature after bias correction. Evaluation of model performance for 95th and 99th percentile maximum temperature and heatwaves showed that most of the models simulate these extremes similar to observation. Northwestern, Central and South-central regions recorded highest number of heatwaves with a frequency of 50 heatwave days/decade, which were captured by the most of the GCMs varying in decadal frequency over the region. Among the GCM, although all models were found competent, ACCESS-ESM1–5, MPI-ESM1–2HR and MRI-ESM2–0 models were found to be the best performing models for extreme indices and heat wave simulation over India. The study will aid to the current understanding of CMIP6-GCMs performances over the different meteorological subdivisions of India and pave way for future projection of heat waves as well as reduction in uncertainty among the models. © 2024 Elsevier B.V.
Hydrogeochemical characterization for groundwater quality and risk assessment in part of central gangetic alluvium, India
(Elsevier B.V., 2024) Sangita Dey; Saumya Singh; N. Janardhana Raju; R.K. Mall
An exponential growth in groundwater extraction will greatly concern the Varuna River basin of Central Ganga alluvium. This complex issue requires proper systematic evaluations to advocate various opportunities for management strategies for groundwater sustainability. The present study aims to convey scientific assessments of the groundwater using different soft-computing techniques to determine its hydrogeochemistry and quality for averting future risk and envisaging suitable management policies. SOM (Self-Organizing Map) model involves characterizing the spatial clusters of regional hydrogeochemistry and reported a gradual increase in salinity from the northwestern to the southeastern part of the area. PCA (Principal Component Analysis) provides evidence of rock-water interactions and anthropogenic activities as responsible factors in determining hydrogeochemistry. Quality assurance is judged by various systematic chemometric indices. CCMEWQI (Canadian Council of Ministers of the Environment Water Quality Index) and IWQI (Irrigation Water Quality Index) reveal that the groundwater is suitable for drinking/domestic and irrigation use. Continuous fluxes of freshwater nourish Gangetic alluvium and generally provide excellent quality. In contrast, the analysis results notice the degradation of drinking quality from the excellent to good category (CCMEWQI) and moderate to low restriction (IWQI) for irrigation suitability. Further study of potential health risks represents the presence of carcinogenic and non-carcinogenic risks for the exposure of NO3−, F−, Pb, and Cr elements. However, the heavy metal pollution and ecological risks are low. Based on the study's findings, the estimates will support initiatives and activities at the local, regional, and national levels, as nations like India need basin-level studies. It is also recommended to consider depth-wise geochemical and temporal chemical variation for further improved studies towards risk assessment. © 2024
Logic gate behavior and intracellular application of a fluorescent molecular switch for the detection of Fe3+ and cascade sensing of F- in pure aqueous media
(Royal Society of Chemistry, 2019) Romi Dwivedi; Divya P. Singh; Saumya Singh; Ashish K. Singh; Brijesh S. Chauhan; S. Srikrishna; Vinod P. Singh
The nature and coordination sites of the Schiff base 3,3′-(1E,1′E)-(1,3-phenylenebis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol (APHN) were tuned by its selective reduction to design a highly efficient fluorescent probe, 3,3′-(pyridine-2,6-diylbis(azanediyl))bis(methylene)dinaphthalen-2-ol (RAPHN). The structures of APHN, RAPHN, and the RAPHN-Fe3+ complex were satisfactorily modeled from the results of density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. RAPHN worked in pure aqueous medium as a turn on-off-on probe of Fe3+ and F-. The fluorescence nature of the probe in the presence and absence of Fe3+/F- was regulated by a set of mechanisms including -CHN isomerization and LMCT. A 2:1 (M:L) binding stoichiometry was established from a fluorescence Job's plot and further substantiated from HR-MS studies. The limits of detection of RAPHN for Fe3+ and RAPHN-Fe3+ for F- were found to be 2.49 × 10-7 M and 1.09 × 10-7 M, respectively. The RAPHN probe caused no cytotoxicity in gut tissue of Drosophila even at high concentrations. The probe displayed excellent bioimaging applications for detection of Fe3+ and F- in gut tissue of Drosophila. A combinatorial logic gate was constructed for the proper understanding of the working principle of RAPHN. © 2019 The Royal Society of Chemistry.
On a class of analytic functions defined by an integral operator
(Hindawi Publishing Corporation, 2013) Pravati Sahoo; Saumya Singh
We define a new subclass M (λ μ, α, β) by using an integral operator Q λμ f (z). We find a coefficient inequality and using that we derive many sharp results. These results generalize many results which are existing in the literature. © 2013 Pravati Sahoo and Saumya Singh.
On a class of harmonic univalent functions defined by a linear operator
(2010) Pravati Sahoo; Saumya Singh
Let SH denote the class of functions f = h + ḡ which are harmonic, univalent and sense preserving in the unit disc Δ. We define a new subclass SHL(α, ß) by using a linear operator of harmonic univalent functions. In this paper, coefficient bounds, distortion bounds and extreme points are obtained. © 2010 Academic Publications.
On a generalized subclass of analytic and bi-univalent functions
(International Publications, 2017) Pravati Sahoo; Saumya Singh; R.N. Mohapatra
In the present paper, we introduce and investigate a new generalized subclass BSh,p(?, µ) of bi-univalent analytic functions in the unit disk U. For functions belonging to the class BSh,p(?, µ), we obtain estimates on the first three Taylor-Maclaurin coefficients |a2|, |a3| and |a4| of f(z), which generalizes some existing results.
pH-Dependent discriminative detection of catecholamine neurotransmitters using 4-boronobenzoic acid functionalized plasmonic silver nanoparticles as a colorimetric probe
(Royal Society of Chemistry, 2025) Saumya Singh; Kaushal Kumar Upadhyay
Catecholamines constitute an important class of biogenic amines functioning both as hormones and as neurotransmitters. Dopamine (DA), norepinephrine (NE), and epinephrine (EP) are the main types. Elevated levels of these neurotransmitters in biological fluids are associated with hypertension, headache, palpitations, spontaneous sweating, anxiety, and even panic attacks. Conversely, their significant depletion may lead to conditions such as Parkinson's disease and dementia. Hence, rapid and accurate detection of these catecholamines is essential for both diagnostic and therapeutic purposes. This work describes the first-ever use of a silver nanoparticle-based selective and sensitive protocol for the simultaneous detection of dopamine (DA), norepinephrine (NE), and epinephrine (EP) in real time. This study explores the behaviour of DA, NE, and EP across a wide pH range (1-14) in the presence and absence of the as-synthesized AgNPs. At the same time, a pH of 9.0 was identified as the optimal pH for their simultaneous detection through three distinct visual color changes supported by UV-Vis measurements. The corresponding limits of detection (LODs) were found to be 92 nM, 93 nM, and 97 nM for DA, NE, and EP, respectively. This approach was further validated by quantifying DA, NE, and EP in their respective injection ampoules as well as spiked blood serum, and the recoveries were found to exceed 90% in all the cases. AgNPs used as the nanosensor were synthesized through a wet chemical approach using 4-formylphenylboronic acid as a stabilizing and reducing agent via Tollen's method at pH 11. The synthesized AgNPs were characterized using spectroscopic and microscopic techniques, viz. FTIR, UV-Vis, XPS, HRMS, SEM, TEM, DLS, EDAX, etc. © 2025 The Royal Society of Chemistry.
Resistance and Subjectivity in Margaret Atwood’s The Testaments
(Springer Nature, 2025) Saumya Singh
The connection between women and nature has persisted throughout history and across cultures, as evidenced in literature and art. However, Western thought has concocted an androcentric mindset that prioritises culture over nature, resulting in human domination of the environment. Challenging this view and recognising our interconnectedness with the ecosystem is vital. By employinging feminist literary criticism, dystopian studies, and ecofeminist criticism, we can deconstruct the symbolic and historical association between women and nature. The Testaments (2019) by Margaret Atwood exemplifies how characters Agnes and Lydia redefine their identities using subversive nature writing to resist victimisation and pursue empowerment. By embracing ecofeminist conceptions and visions, we can spotlight the need for equity among marginalised groups and reflect on the destructive influence of androcentrism. This chapter explores ecofeminist conceptions and visions in Atwood’s novel to show the fallacious view of androcentrism and revive alternative perspectives. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Pte Ltd. 2024.