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result(s) for
"Tiwari, Umesh K."
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L-cysteine/MoS2 modified robust surface plasmon resonance optical fiber sensor for sensing of Ferritin and IgG
2023
L-cysteine conjugated molybdenum disulphide (MoS
2
) nanosheets have been covalently attached to a gold coated surface plasmon resonance (SPR) optical fiber to prepare a robust and stable sensor. Owing to the multifunctionality of the deposited nanosheet conjugate, the antibodies are also covalently conjugated in the subsequent step to realize the design of a SPR optical fiber biosensor for the two important bioanalytes namely, Ferritin and Immunoglobin G (IgG). The different stages of the biosensor preparation have been characterized and verified with microscopic and spectroscopic techniques. A uniform and stable deposition of the L-cysteine/MoS
2
nanosheets has allowed the biosensor to be reused for multiple times. Unlike the peeling-off of the MoS
2
coatings from the gold layer reported previously in the case of physically adsorbed nanomaterial, the herein adopted strategy addresses this critical concern. It has also been possible to use the single SPR fiber for both Ferritin and IgG bioassay experiments by regenerating the sensor and immobilizing two different antibodies in separate steps. For ferritin, the biosensor has delivered a linear sensor response (SPR wavelength shifts) in the concentration range of 50–400 ng/mL, while IgG has been successfully sensed from 50 to 250 µg/mL. The limit of detection for Ferritin and IgG analysis have been estimated to be 12 ng/mL and 7.2 µg/mL, respectively. The biosensors have also been verified for their specificity for the targeted molecule only. A uniform and stable deposition of the nanomaterial conjugate, reproducibility, regeneration capacity, a good sensitivity, and the specificity can be highlighted as some of key features of the L-cysteine/MoS
2
optical fiber biosensor. The system can be advocated as a useful biosensor setup for the sensitive biosensing of Ferritin and IgG.
Journal Article
Diffusion controlled electrochemical analysis of MoS2 and MOF derived metal oxide–carbon hybrids for high performance supercapacitors
by
Shrivastav, Vaishali
,
Kaur, Ashwinder
,
Tiwari, Umesh K.
in
639/301/299
,
639/301/357
,
639/638/161
2023
In the context of emerging electric devices, the demand for advanced energy storage materials has intensified. These materials must encompass both surface and diffusion-driven charge storage mechanisms. While diffusion-driven reactions offer high capacitance by utilizing the bulk of the material, their effectiveness diminishes at higher discharge rates. Conversely, surface-controlled reactions provide rapid charge/discharge rates and high power density. To strike a balance between these attributes, we devised a tri-composite material, TiO
2
/Carbon/MoS
2
(T10/MoS
2
). This innovative design features a highly porous carbon core for efficient diffusion and redox-active MoS
2
nanosheets on the surface. Leveraging these characteristics, the T10/MoS
2
composite exhibited impressive specific capacitance (436 F/g at 5 mV/s), with a significant contribution from the diffusion-controlled process (82%). Furthermore, our symmetrical device achieved a notable energy density of ~ 50 Wh/kg at a power density of 1.3 kW/kg. This concept holds promise for extending the approach to other Metal–Organic Framework (MOF) structures, enabling enhanced diffusion-controlled processes in energy storage applications.
Journal Article
Copper foam supported g-C3N4-metal–organic framework bacteria biohybrid cathode catalyst for CO2 reduction in microbial electrosynthesis
2023
Microbial electrosynthesis (MES) presents a versatile approach for efficiently converting carbon dioxide (CO
2
) into valuable products. However, poor electron uptake by the microorganisms from the cathode severely limits the performance of MES. In this study, a graphitic carbon nitride (
g-
C
3
N
4
)-metal–organic framework (MOF)
i.e.
HKUST-1 composite was newly designed and synthesized as the cathode catalyst for MES operations. The physiochemical analysis such as X-ray diffraction, scanning electron microscopy (SEM), and X-ray fluorescence spectroscopy showed the successful synthesis of
g-
C
3
N
4
-HKUST-1, whereas electrochemical assessments revealed its enhanced kinetics for redox reactions. The
g-
C
3
N
4
-HKUST-1 composite displayed excellent biocompatibility to develop electroactive biohybrid catalyst for CO
2
reduction. The MES with
g-
C
3
N
4
-HKUST-1 biohybrid demonstrated an excellent current uptake of 1.7 mA/cm
2
, which was noted higher as compared to the MES using
g-
C
3
N
4
biohybrid (1.1 mA/cm
2
). Both the MESs could convert CO
2
into acetic and isobutyric acid with a significantly higher yield of 0.46 g/L.d and 0.14 g/L.d respectively in MES with
g-
C
3
N
4
-HKUST-1 biohybrid and 0.27 g/L.d and 0.06 g/L.d, respectively in MES with
g-
C
3
N
4
biohybrid. The findings of this study suggest that
g-
C
3
N
4
-HKUST-1 is a highly efficient catalytic material for biocathodes in MESs to significantly enhance the CO
2
conversion.
Journal Article
Two-dimensional transition metal dichalcogenides assisted biofunctionalized optical fiber SPR biosensor for efficient and rapid detection of bovine serum albumin
by
Tiwari, Umesh K.
,
Deep, Akash
,
Sinha, Ravindra K.
in
140/133
,
639/624/1111/55
,
639/925/357/1018
2019
The present study reports an alternative method of functionalizing the optical fiber Surface Plasmon Resonance (SPR) sensing probe with antibodies for label-free detection of bovine serum albumin (BSA) protein. In this novel approach, the gold coated fiber was first modified with Molybdenum disulfide (MoS
2
) nanosheets followed by its bio-functionalization with Anti-BSA antibodies. The developed technique not only allowed the amplification of the SPR signals by synergic effects of MoS
2
and gold metallic thin film but also enabled a direct and chemical-free attachment of representative antibodies through hydrophobic interactions. The sensitivity of the MoS
2
modified sensing probe with detection limit of 0.29 µg/mL was improved as compared to the fiber optic SPR biosensor without MoS
2
overlayer (Detection limit for BSA was 0.45 μg/mL). The developed biosensor has good specificity, and environmental stability. Accordingly, the proposed design of the MoS
2
based SPR optical biosensor can offer the development of a simplified optical device for the monitoring of various biomedical and environmental parameters.
Journal Article
Fuel adulteration detection sensor using sensitivity-optimized etched long-period fiber grating
by
Singh, Sartajvir
,
Prashar, Shivendu
,
Tiwari, Umesh K.
in
Chromatography
,
Cladding
,
Coupled modes
2024
The adulteration of cheap solvents in petrol for financial benefit is not legally allowed because it generates harmful air pollutants in the emission. In the present work, a long-period fiber grating (LPFG)-based sensor is proposed to quantify the adulteration of kerosene oil in petrol. The vector coupled-mode theory has been implemented on a 3-layer fiber geometry-based mathematical approach to estimate the refractive index (RI) sensitivity. For quantitative analysis, the RI sensitivities of LPFG-based cladding modes (
HE
15
-
HE
17
)
have been analyzed while considering important LPFG parameters i.e., optical mode order grating period, and cladding radius. The dependency of LPFG response on aforesaid parameters leads to their critical selection for designing a highly sensitive adulteration sensor. It is apparent that the higher-ordered (
HE
17
)
cladding mode has achieved the highest RI sensitivity of 3071.6 nm/RIU (nanometer per refractive index unit) at cladding radius 32.5 μm and grating period 330 μm. It derives the LPFG sensor’s resolution to 0.676 nm for per percentage (nm/%) adulteration of kerosene in petrol. With this resolution, the kerosene adulteration of less than 10% in petrol can be easily detected. Therefore, this study envisages a design to fabricate LPFG sensors for adulteration detection with utmost precision at fuel filling stations.
Graphical Abstract
Journal Article
L-cysteine/MoS 2 modified robust surface plasmon resonance optical fiber sensor for sensing of Ferritin and IgG
by
Deep, Akash
,
Tiwari, Umesh K
,
Thawany, Priyanka
in
Biosensing Techniques
,
Cysteine
,
Ferritins
2023
L-cysteine conjugated molybdenum disulphide (MoS
) nanosheets have been covalently attached to a gold coated surface plasmon resonance (SPR) optical fiber to prepare a robust and stable sensor. Owing to the multifunctionality of the deposited nanosheet conjugate, the antibodies are also covalently conjugated in the subsequent step to realize the design of a SPR optical fiber biosensor for the two important bioanalytes namely, Ferritin and Immunoglobin G (IgG). The different stages of the biosensor preparation have been characterized and verified with microscopic and spectroscopic techniques. A uniform and stable deposition of the L-cysteine/MoS
nanosheets has allowed the biosensor to be reused for multiple times. Unlike the peeling-off of the MoS
coatings from the gold layer reported previously in the case of physically adsorbed nanomaterial, the herein adopted strategy addresses this critical concern. It has also been possible to use the single SPR fiber for both Ferritin and IgG bioassay experiments by regenerating the sensor and immobilizing two different antibodies in separate steps. For ferritin, the biosensor has delivered a linear sensor response (SPR wavelength shifts) in the concentration range of 50-400 ng/mL, while IgG has been successfully sensed from 50 to 250 µg/mL. The limit of detection for Ferritin and IgG analysis have been estimated to be 12 ng/mL and 7.2 µg/mL, respectively. The biosensors have also been verified for their specificity for the targeted molecule only. A uniform and stable deposition of the nanomaterial conjugate, reproducibility, regeneration capacity, a good sensitivity, and the specificity can be highlighted as some of key features of the L-cysteine/MoS
optical fiber biosensor. The system can be advocated as a useful biosensor setup for the sensitive biosensing of Ferritin and IgG.
Journal Article
Copper foam supported g-C 3 N 4 -metal-organic framework bacteria biohybrid cathode catalyst for CO 2 reduction in microbial electrosynthesis
by
Giri, Balendu Sekhar
,
Holdynski, Marcin
,
Tiwari, Umesh K
in
Bacteria
,
Carbon Dioxide - chemistry
,
Copper - chemistry
2023
Microbial electrosynthesis (MES) presents a versatile approach for efficiently converting carbon dioxide (CO
) into valuable products. However, poor electron uptake by the microorganisms from the cathode severely limits the performance of MES. In this study, a graphitic carbon nitride (g-C
N
)-metal-organic framework (MOF) i.e. HKUST-1 composite was newly designed and synthesized as the cathode catalyst for MES operations. The physiochemical analysis such as X-ray diffraction, scanning electron microscopy (SEM), and X-ray fluorescence spectroscopy showed the successful synthesis of g-C
N
-HKUST-1, whereas electrochemical assessments revealed its enhanced kinetics for redox reactions. The g-C
N
-HKUST-1 composite displayed excellent biocompatibility to develop electroactive biohybrid catalyst for CO
reduction. The MES with g-C
N
-HKUST-1 biohybrid demonstrated an excellent current uptake of 1.7 mA/cm
, which was noted higher as compared to the MES using g-C
N
biohybrid (1.1 mA/cm
). Both the MESs could convert CO
into acetic and isobutyric acid with a significantly higher yield of 0.46 g/L.d and 0.14 g/L.d respectively in MES with g-C
N
-HKUST-1 biohybrid and 0.27 g/L.d and 0.06 g/L.d, respectively in MES with g-C
N
biohybrid. The findings of this study suggest that g-C
N
-HKUST-1 is a highly efficient catalytic material for biocathodes in MESs to significantly enhance the CO
conversion.
Journal Article
An Improved Version of the Prewhitening Method for Trend Analysis in the Autocorrelated Time Series
by
Sheoran, Rahul
,
Hooda, Rakesh K.
,
Tiwari, Rakesh K.
in
auto correlation
,
Autocorrelation
,
Autoregressive processes
2024
Nonparametric trend detection tests like the Mann–Kendall (MK) test require independent observations, but serial autocorrelation in the datasets inflates/deflates the variance and alters the Type-I and Type-II errors. Prewhitening (PW) techniques help address this issue by removing autocorrelation prior to applying MK. We evaluate several PW schemes—von Storch (PW-S), Slope-corrected PW (PW-Cor), trend-free prewhitening (TFPW) proposed by Yue (TFPW-Y), iterative TFPW (TFPW-WS), variance-corrected TFPW (VCTFPW), and newly proposed detrended prewhitened with modified trend added (DPWMT). Through Monte Carlo simulations, we constructed a lag-1 autoregressive (AR(1)) time series and systematically assessed the performance of different PW methods relative to sample size, autocorrelation, and trend slope. Results indicate that all methods tend to overestimate weak trends in small samples (n < 40). For moderate/high trends, the slopes estimated from the VCTFPW and DPWMT series close (within a ± 20% range) to the actual trend. VCTFPW shows slightly lower RMSE than DPWMT at mid-range lag-1 autocorrelation (ρ1 = 0.3 to 0.6) but fluctuates for ρ1 ≥ 0.7. Original series and TFPW-Y fail to control Type-I error with increasing ρ1, while VCTFPW and DPWMT maintained Type-I errors below the significance level (α = 0.05) for large samples. Apart from TFPW-Y, all PW methods resulted in weak power of the test for weak trends and small samples. TFPW-WS showed high power of the test but only for strong autocorrelated data combined with strong trends. In contrast, VCTFPW failed to preserve the power of the test at high autocorrelation (≥0.7) due to slope underestimation. DPWMT restores the power of the test for 0.1 ≤ ρ1 ≤ 0.9 for moderate/strong trends. Overall, the proposed DPWMT approach demonstrates clear advantages, providing unbiased slope estimates, reasonable Type-I error control, and sufficient power in detecting linear trends in the AR(1) series.
Journal Article
Root system architecture for abiotic stress tolerance in potato: Lessons from plants
by
Poonia, Anuj K.
,
Luthra, Satish K.
,
Bhatia, Nisha
in
Abiotic stress
,
Agricultural production
,
Cereals
2022
The root is an important plant organ, which uptakes nutrients and water from the soil, and provides anchorage for the plant. Abiotic stresses like heat, drought, nutrients, salinity, and cold are the major problems of potato cultivation. Substantial research advances have been achieved in cereals and model plants on root system architecture (RSA), and so root ideotype (e.g., maize) have been developed for efficient nutrient capture to enhance nutrient use efficiency along with genes regulating root architecture in plants. However, limited work is available on potatoes, with a few illustrations on root morphology in drought and nitrogen stress. The role of root architecture in potatoes has been investigated to some extent under heat, drought, and nitrogen stresses. Hence, this mini-review aims to update knowledge and prospects of strengthening RSA research by applying multi-disciplinary physiological, biochemical, and molecular approaches to abiotic stress tolerance to potatoes with lessons learned from model plants, cereals, and other plants.
Journal Article
Processed dietary fiber partially hydrolyzed guar gum increases susceptibility to colitis and colon tumorigenesis in mice
2025
The vital role of naturally occurring dietary fibers (DFs) in maintaining intestinal health has fueled the incorporation of refined DFs into processed foods. The present study assessed the impact of purified DF partially hydrolyzed guar gum (Phgg) on intestinal inflammation and colitis-associated colon carcinogenesis (CAC). Surprisingly, wild-type mice fed Phgg exhibited more severe dextran sulfate sodium (DSS)-induced colitis than the control group. Additionally, Phgg feeding led to increased colonic expression of genes promoting cell proliferation. Accordingly, extensive colon tumorigenesis was observed in Phgg-fed mice in the azoxymethane (AOM)/DSS model, whereas the control group exhibited no visible tumors. Mice fed low-Phgg (2.5%) diet exhibited more colitis and tumorigenesis than controls, but less than those on regular Phgg diet (7.5%), suggesting a dose-dependent influence of Phgg on colitis and CAC development. Our study reveals that Phgg supplementation exacerbates colitis and promotes colon tumorigenesis, warranting further investigation into the potential gastrointestinal health risks associated with processed Phgg consumption.
Journal Article