3,096 results on '"Kumar, Amit"'
Search Results
202. Mehar approach to solve neutrosophic linear programming problems using possibilistic mean.
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Bhatia, Tanveen Kaur, Kumar, Amit, Sharma, M. K., and Appadoo, S. S.
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ATTITUDE (Psychology) - Abstract
Khatter (Soft Comput 24:6847–16,867, 2020) pointed out that although several approaches are proposed in the literature to solve single-valued neutrosophic linear programming problems (SVNLPPS) (linear programming problems in which all the parameters except decision variables are either represented by single-valued triangular neutrosophic numbers (SVTNNS) or single-valued trapezoidal neutrosophic numbers (SVTrNNS)). However, all the methods for comparing single-valued neutrosophic numbers (SVNNS), used in existing approaches, are independent from the attitude of the decision-maker towards the risk. To fill this gap, Khatter (2020), firstly, proposed a method for comparing two SVNNS by considering the attitude of the decision-maker towards the risk. Then, using the proposed comparing method, Khatter (2020) proposed an approach to solve SVNLPPS. In this paper, it is pointed out that a mathematical incorrect result is considered in Khatter's approach. Hence, it is inappropriate to use Khatter's approach. Also, it is pointed out that some mathematical incorrect results are considered in other existing approaches for solving SVNLPPS. Hence, it is inappropriate to use other existing approaches for solving SVNLPPS. Furthermore, to resolve the inappropriateness of Khatter's approach and other existing approaches, a new approach (named as Mehar approach) is proposed to solve SVNLPPS. Finally, correct optimal solution of some existing SVNLPPS is obtained by the proposed Mehar approach. [ABSTRACT FROM AUTHOR]
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- 2022
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203. Comparative power quality analysis of conventional and proposed enhanced SRF SOGI-FLL control based DSTATCOM.
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Kumar, Amit and Kumar, Pradeep
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SLIDING mode control , *PULSE width modulation transformers , *POWER electronics - Abstract
This paper expresses about comparative power quality analysis in between conventional and proposed control techniques of DSTATCOM under different loading conditions. The goal of DSTATCOM is to reduce power quality problems that occur due to an unbalanced load, nonlinear load, power electronics based load, and polluted grid. The performances of DSTATCOM are different in the different control techniques. Three conventional and one proposed control techniques have been employed in the DSTATCOM. Synchronous reference frame (SRF), sliding mode control (SMC), and ADALINE based LMS control are the conventional techniques, while enhanced SRF SOGI-FLL is the proposed technique. The control techniques of DSTATCOM have been compared in terms of load balancing, power factor enhancement, DC link voltage regulation, and minimization of harmonics. These control techniques extract reference current for the PWM which generates switching pulses for the DSTATCOM. The complete H-bridge DSTATCOM system along with these control techniques have been implemented in MATLAB /Simulink platform, and, after execution, superior power quality features of proposed control technique have been investigated. [ABSTRACT FROM AUTHOR]
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- 2022
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204. Structural evolution of in situ polymerized poly(L-lactic acid) nanocomposite for smart textile application.
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Hazarika, Doli, Kumar, Amit, and Katiyar, Vimal
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LACTIC acid , *POLYMERIZATION , *NANOCOMPOSITE materials , *METHYLENE blue , *NONWOVEN textiles , *TITANIUM oxides , *CONTACT angle , *NATURAL dyes & dyeing - Abstract
This present study demonstrated the preparation of a highly crystalline anatase (ana) form of titanium oxide (TiO2) doped silk nanocrystal (SNC) nanohybrid (ana-TCS) of diameter (7.5 ± 1.4 nm) by the sol–gel method using titanium (IV) butoxide as the hydrolysis material. This prepared nanohybrid with surface hydroxyl groups acted as a co-initiator for the synthesis of poly(L-lactic acid) (PLLA)-g-ana-TSC nanocomposite with grafted PLLA chains via the in situ polymerization technique, using tin-octoate as a catalyst. The fabricated nanocomposite had a high number average molecular weight of 83 kDa with good processibility. This prepared nanocomposite was hydrophobic in nature, with a contact angle of 105°, which was further enhanced to 122 ± 1° when processed via electrospinning technique into a non-woven fabric. The prepared nanocomposite could degrade up to 43% methylene blue dye in 15 days. This nanocomposite showed no significant molecular weight reduction after 1 h of aqeous treatment, which could be attributed to its hydrophobic nature, inhibiting its degradation. However, 50% degradation was observed for the nanocomoposite whereas, PLLA demonstrated 25% degradation in 15 days, after its end-of-life. Thus, this study revealed that the in situ synthesized PLA-ana-TCS nanocomposite could be targeted for use as a hydrophobic, self-cleaning, dye-degradable fabric. [ABSTRACT FROM AUTHOR]
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- 2022
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205. Analysing frequent extreme flood incidences in Brahmaputra basin, South Asia.
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Kumar, Amit, Mondal, Subhasree, and Lal, Preet
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FLOODS , *SYNTHETIC aperture radar , *SNOWMELT , *NATURAL disasters , *SNOW cover , *LAND cover - Abstract
The present study is focused on the flood inundation in Brahmaputra Basin, which is one of the most recurrent and destructive natural disasters of the region. The flood inundation was assessed using C-Band Sentinel 1A synthetic aperture radar (SAR) during 2015–2020 with precipitation patterns, runoff discharge, and their impacts on land cover in the basin. The study exhibited a very high precipitation during monsoon in the upper catchment resulting in severe flood inundation in downslopes of Brahmaputra Basin. A very high (900–2000 mm) to extremely high (>2000 mm) monthly cumulative precipitation in the south and south-eastern parts of basin led to high discharge (16,000 to 18,000 m3s-1) during July-August months. The river discharge increases with cumulative effects of precipitation and melting of snow cover during late summer and monsoon season, and induced flood inundation in lower parts of basin. This flood has largely affected agricultural land (>77% of total basin), forests (~3%), and settlement (426 to 1758 km2) affecting large wildlife and livelihood during 2015–2020. The study highlights the regions affected with recurrent flood and necessitates adopting an integrated, multi-hazard, multi-stakeholder approach with an emphasis on self-reliance of the community for sustenance with local resources and practices. [ABSTRACT FROM AUTHOR]
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- 2022
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206. Solid-State Reaction Synthesis of Nanoscale Materials: Strategies and Applications.
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Kumar, Amit, Dutta, Soumen, Kim, Seonock, Kwon, Taewan, Patil, Santosh S., Kumari, Nitee, Jeevanandham, Sampathkumar, and Lee, In Su
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Nanomaterials (NMs) with unique structures and compositions can give rise to exotic physicochemical properties and applications. Despite the advancement in solution-based methods, scalable access to a wide range of crystal phases and intricate compositions is still challenging. Solid-state reaction (SSR) syntheses have high potential owing to their flexibility toward multielemental phases under feasibly high temperatures and solvent-free conditions as well as their scalability and simplicity. Controlling the nanoscale features through SSRs demands a strategic nanospace-confinement approach due to the risk of heat-induced reshaping and sintering. Here, we describe advanced SSR strategies for NM synthesis, focusing on mechanistic insights, novel nanoscale phenomena, and underlying principles using a series of examples under different categories. After introducing the history of classical SSRs, key theories, and definitions central to the topic, we categorize various modern SSR strategies based on the surrounding solid-state media used for nanostructure growth, conversion, and migration under nanospace or dimensional confinement. This comprehensive review will advance the quest for new materials design, synthesis, and applications. [ABSTRACT FROM AUTHOR]
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- 2022
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207. Medicare Claim–Based National Institutes of Health Stroke Scale to Predict 30-Day Mortality and Hospital Readmission.
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Kumar, Amit, Roy, Indrakshi, Bosch, Pamela R., Fehnel, Corey R., Garnica, Nicholas, Cook, Jon, Warren, Meghan, and Karmarkar, Amol M.
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PATIENT readmissions , *HOSPITAL mortality , *MEDICARE , *ISCHEMIC stroke , *MEDICARE beneficiaries - Abstract
Background: The Centers for Medicare and Medicaid Services (CMS) penalizes hospitals for higher than expected 30-day mortality rates using methods without accounting for condition severity risk adjustment. For patients with stroke, CMS claims did not quantify stroke severity until recently, when the National Institutes of Health Stroke Scale (NIHSS) reporting began. Objective: Examine the predictive ability of claim-based NIHSS to predict 30-day mortality and 30-day hospital readmission in patients with ischemic stroke. Design: Retrospective cohort study of Medicare claims data. Patients: Medicare beneficiaries with ischemic stroke (N=43,241) acute hospitalization between October 2016 and November 2017. Measurements: All-cause 30-day mortality and 30-day hospital readmission. NIHSS score was derived from ICD-10 codes and stratified into the following: minor to moderate, moderate, moderate to severe, and severe categories. Results: Among 43,241 patients with ischemic stroke with NIHSS from 2,659 US hospitals, 64.6% had minor to moderate stroke, 14.3% had moderate, 12.7% had moderate to severe, and 8.5% had a severe stroke,10.1% died within 30 days, 12.1% were readmitted within 30 days. The NIHSS exhibited stronger discriminant property (C-statistic 0.83, 95% CI: 0.82–0.84) for 30-day mortality compared to Elixhauser (0.74, 95% CI: 0.73–0.75). A monotonic increase in the adjusted 30-day mortality risk occurred relative to minor to moderate stroke category: hazard ratio [HR]=2.92 (95% CI=2.59–3.29) for moderate stroke, HR=5.49 (95% CI=4.90–6.15) for moderate to severe stroke, and HR=7.82 (95% CI=6.95–8.80) for severe stroke. After accounting for competing risk of mortality, there was a significantly higher readmission risk in the moderate stroke (HR=1.11, 95% CI=1.03–1.20), but significantly lower readmission risk in the severe stroke (HR=0.84, 95% CI=0.74–0.95) categories. Limitation: Timing of NIHSS reporting during hospitalization is unknown. Conclusions: Medicare claim–based NIHSS is significantly associated with 30-day mortality in Medicare patients with ischemic stroke and significantly improves discriminant property relative to the Elixhauser comorbidity index. [ABSTRACT FROM AUTHOR]
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- 2022
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208. Characteristics of Various Losses of Axial Piston Pump and Bent Axis Hydro-motor with respect to Displacement Conditions and Load Demands.
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Pandey, Ajit Kumar, Kumar, Amit, and Kumar, Ajit
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RECIPROCATING pumps , *HYDRAULIC control systems , *BOND graphs , *HYDRAULIC circuits , *HYDRAULIC drive , *VARIABLE speed drives , *MOTORS - Abstract
The hydrostatic transmission is one of the most important applications in the fluid power systems. It gives smooth change in output speed, torque and power as per the design requirements. Present article deals with various losses of the hydraulic pump and motor using a closed circuit hydraulic drive. The drive basically consists of a variable displacement axial piston pump that supplies pressurized fluid to a variable displacement bent axis hydro-motor. In investigating the pump/motor performance, bond graph simulation technique is used to model the drive system. Various losses of the pump and motor are accounted in the model by suitable resistive elements. The characteristics of them are identified through experiments. The predicted performance of the pump/motor is studied with respect to the displacement and load at the same time they are validated experimentally. The investigation made in the article identifies the control strategy which will be useful for the practicing engineers to select best combination of the pump and motor displacement for optimizing the drive performance and minimizing the losses as well. The study performed in this research work will be useful for the similar hydraulic configuration used in mobile equipment. [ABSTRACT FROM AUTHOR]
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- 2022
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209. Updated meta‐analysis on the diagnostic accuracy of serum anti‐Mullerian hormone in poly cystic ovary syndrome involving 13 509 subjects.
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Anand, Shikha, Kumar, Amit, Prasad, Anupa, and Trivedi, Kiran
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ONLINE information services , *MEDICAL databases , *POLYCYSTIC ovary syndrome , *META-analysis , *SYSTEMATIC reviews , *RISK assessment , *SEX hormones , *DIAGNOSTIC errors , *MEDLINE , *HYPERANDROGENISM ,RESEARCH evaluation - Abstract
Aim: To determine the diagnostic accuracy of anti‐Mullerian hormone (AMH) in the diagnosis of polycystic ovary syndrome (PCOS). Methods: Two independent reviewers searched the electronic databases and search engines using PubMed, Cochrane library, and Google Scholar systematically to retrieve relevant articles published from inception to September 2021. The diagnostic efficacy of AMH was computed using the random‐effects model in terms of pooled sensitivity, specificity, and diagnostic odds ratio (DOR) with 95% confidence interval (CI). A meta‐regression and subgroup analysis were performed to check for any source which could explain possible heterogeneity. Risk of bias assessment was conducted using the QUADAS‐2 tool recommended by Cochrane Library. Results: This meta‐analysis included a total of 41 studies involving 13 509 subjects. We observed promising pooled sensitivity 0.78 (95% CI 0.74 to 0.81), specificity 0.87 (95% CI 0.84 to 0.90), and diagnostic odds ratio (DOR) 24 (95% CI 15 to 37), for AMH in detecting PCOS and discriminatory power (summary receiver operating characteristic [SROC] curves, 0.89 [95% CI 0.86–0.92]). The most prominent bias was noted in the patient selection and index test assessment. Conclusions: With the findings of this current meta‐analysis, we conclude serum AMH to be a promising biomarker for the diagnosis of PCOS, however, substantial heterogeneity among studies needs individual patient data analysis in order to identify an optimal cut‐off value and homogenous findings. Registration Number and Guidelines: This meta‐analysis was performed according to constructed protocol registered in the PROSPERO database with registration number CRD42021246910. [ABSTRACT FROM AUTHOR]
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- 2022
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210. Assessment of free radicals and reactive oxygen species milieu in nanoparticles adjuvanted outer membrane proteins vaccine against Salmonella typhi.
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Singh, Yashpal, Kumar, Amit, Saxena, Anjani, Bhatt, Pankaj, Singh, S. P., Kumar, Avadhesh, Mrigesh, Meena, and Saxena, Mumtesh Kumar
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In this study, calcium phosphate nanoparticles-based (STCNV) and montanide oil adjuvant vaccine (STOAV) containing outer membrane proteins (Omps) of S. Typhi were evaluated for inducing oxidative stress indicators [reduced glutathione (GSH), lipid peroxidation (LPO), catalase, superoxide dismutase (SOD), and total protein] in the tissues of mice after vaccination. The GSH levels though slightly high in the liver, kidney, and lungs of STCNV group were not significantly different from STOAV and the control group (STC). There was no significant difference in LPO levels in any group for any tissue. The significantly lower activities of catalase were observed in the kidney and lungs of the STCNV group as compared to STOAV and STC group, while in the liver, STCNV group revealed lower catalase activity in comparison to the control group. No significant difference in the SOD activities between the two vaccinated groups was observed. The total protein contents in all the organs showed no significant difference in the vaccinated and the control group. The vaccines may induce long-term inflammatory response and consequently damage vital organs; this study revealed no long-term oxidative stress in all the three vital organs, suggesting that these vaccines may not cause oxidative damages in the vital organs of mice. [ABSTRACT FROM AUTHOR]
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- 2022
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211. Elucidation of molecular and physiological mechanisms addressing integrated omic approaches for heavy metal stress tolerance in crops.
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Mondal, Raju, Kumar, Amit, Shabnam, Aftab Ahmad, and Chaturvedi, Ashish K.
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PHYSIOLOGY , *HEAVY metals , *HEAVY metal toxicology , *PHOTOSYSTEMS , *CROPS - Abstract
Recent industrialisation has seen an alarming increase in heavy metal pollution, raising the question of how to sustain food production in the presence of heavy metals. Several reviews have addressed the direct and indirect effects of heavy metals on crop physiological and biochemical processes. However, understanding of the physiological and molecular mechanisms requires integrating omic approaches to explore the target mechanism in general in crops, and those insights are still lacking. To date, most of the information related to omic approaches about heavy metals has been sparse and sporadic. This review, by means of examples, attempts to integrate different available proteomic, transcriptomic and genomic approaches in a nutshell along with underlying physiological and molecular mechanisms occurring in crops. Major identified transcription factors (TFs) (MYBs, WRKYs), transgenes (MT2 , Nramp6 , GSTU3 , CIPK , MYB1 and DRE), up-regulated (CAT, SODs, POD and APX), down-regulated (ATPase subunits, Rubisco subunits and photosystem I (PSI) reaction centre) proteins, and miRNA (miR397, miR398a, miR408, OsmiR601 and miR166) for major heavy metals have been summarised. It provides a mode of action of heavy metals and their fate inside the plant. It also elucidates how these omics approaches facilitate in mitigating heavy metal stress and could help in addressing crop tolerance based on these mechanisms. Identifying donors with the aid of novel omic approaches could be useful for the development of HM tolerant crops, promoting future sustainability in heavy-metal-polluted soil and water resources. The recent increasing trend of industrialisation has imposed heavy metal pollution that has affected crop productivity worldwide. Understanding the physiological and molecular mechanism through omic approaches is a prerequisite to improve the target mechanism in crops, which is still lacking. The present manuscript emphasises the current understanding of physiological and molecular mechanisms and proposes an integrated omic study to improve the sustainability of crop production. [ABSTRACT FROM AUTHOR]
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- 2022
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212. Weed Management through Imidazolinones in Pigeon Pea (Cajanus cajan L.).
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Kumar, Amit, Dhaka, A. K., Kumar, Satish, Vats, Akshay Kumar, and Harender
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WEED control , *LEGUMES , *WEEDS , *PIGEON pea , *NUTRIENT uptake , *SEED yield , *IMAZETHAPYR - Abstract
Background: Pulse crops are commonly known as poor man’s meat. Pigeon pea is second most important pulse crops of India after chickpea. Weeds are amongst prime biotic factors limiting pigeon pea yield and can cause seed yield losses up to 80 per cent. Promising result of weed control by pendimethalin was documented in pigeon pea. Also Imazethapyr is applied as pre and post emergence to control grasses and broad leaved weeds in other pulse crops but limited research was undertaken in pigeon pea. Therefore, current experiment focused to compare the effect of imidazolinones alone and in combination in pigeon pea. Methods: To control weeds in pigeon pea, pre and post-emergence of imidazolinones alone and in combination with pendimethalin was applied. Nutrient content, nutrient uptake, productivity and economics of pigeon pea were worked out. Conclusion: Among herbicidal treatments, the highest nutrient content, nutrient uptake, productivity, net returns and benefit cost ratio in pigeon pea were observed in the pre-emergence application of pendimethalin + imazethapyr @ 1000 + 75 g ha-1. Therefore, this treatment may be an effective and profitable alternative to the existing manual and costlier recommendation (two hoeing at 25 and 45 DAS) of weed control in pigeon pea in Haryana locality. [ABSTRACT FROM AUTHOR]
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- 2022
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213. Blast Waves in Two and Three Dimensions: Euler Versus Navier–Stokes Equations.
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Kumar, Amit and Rajesh, R.
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NAVIER-Stokes equations , *BLAST waves , *EULER equations , *GAS dynamics , *MOLECULAR dynamics , *HEAT conduction , *CLASSICAL mechanics - Abstract
The exact solution of the Euler equation, which describes the time evolution of a blast wave created by an intense explosion, is a classic problem in gas dynamics. However, it has been found that the analytical results do not match with results from molecular dynamics simulation of hard spheres in two and three dimensions. In this paper, we show that the mismatch between theory and simulations can be resolved by considering the Navier–Stokes equation. From the direct numerical simulation of the Navier–Stokes equation in two and three dimensions, we show that the inclusion of heat conduction and viscosity terms is essential to capture the results from molecular dynamics simulations. [ABSTRACT FROM AUTHOR]
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- 2022
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214. Estimation of Biomass and Soil Carbon Stock in the Hydroelectric Catchment of India and its Implementation to Climate Change.
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Kumar, Amit and Kumar, Munesh
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BIOMASS estimation , *CARBON in soils , *CLIMATE change , *FOREST density , *GREENHOUSE gases - Abstract
A few decades ago, hydroelectric projects were considered a clean source of energy. The present study aims to assess the biomass and soil carbon (C) stock in the hydroelectric catchment in India and further, its implications to mitigate GHG emissions. The estimation depicts the low 'C' stock in the reservoir's catchment in comparison to reservoirs located globally in the same eco-region which will ultimately result in lower GHG emission in the future. Moreover, estimated total carbon density of the forest species was found as 54.92 ± 18.07 MgC.ha−1 while mean SOC was 79.64 ± 19.32 MgC.ha−1. The average total 'C' stock of Tehri hydroelectric reservoir's catchment was estimated as 134.56 MgC.ha−1. Moreover, ratios (total flooded carbon/installed capacity) comprised between 4 and304 kgC/W from the other reservoirs reported globally. These ratios are higher than the Tehri reservoir (0.28 kgC/W) as flooded area of Tehri reservoir during impoundment was 52 km2. Thus, Tehri reservoir was found to emit less GHG in time to come. The present study helps the hydropower industries, policymakers, and environmentalists in designing the catchment area treatment plan to minimize the negative impact of GHG on climate change. [ABSTRACT FROM AUTHOR]
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- 2022
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215. Conducting Polymer‐Based Micro‐ and Nano‐batteries for Biomedical Applications: A Short Review.
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Singh, Neetika, Kumar, Amit, and Riaz, Ufana
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CONDUCTING polymers , *SMART devices , *INORGANIC compounds , *ELECTRONIC equipment , *ENERGY conversion , *ARTIFICIAL implants , *ELECTRIC batteries , *NANOMECHANICS - Abstract
Current advancements in nanotechnology focus on miniaturization of electronic devices to provide power on demand. The Li+ ion based micro/nano‐batteries are excellent candidates for this purpose. However, the manufacture a single nano‐battery with assured reliable performance is one of the greatest challenges faced in the fabrication of Li+ ion based nano‐batteries. Nanostructured conducting polymers (NCPs) have shown promise in many frontier areas such as biosensors, microelectronics, polymer batteries, actuators, energy conversion etc. The combination of NCPs with inorganic compounds for designing nano‐batteries has been the subject of extensive investigation due to synergistic interaction of NCPs with inorganic compounds that provides remarkable improvement in electrode lifetime, rate capabilities, and voltage as well as mechanical and thermal stability. The present mini review deals with the fabrication of nano‐batteries using polypyrrole (PPy), polyaniline (PANI), and polythiophene (PTh) which could be utilized for various biomedical applications. The design and development of nano‐batteries using NCPs is discussed along with their applications in implantable devices, pace makers, smart sensing devices etc. [ABSTRACT FROM AUTHOR]
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- 2022
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216. H19 inhibition increases HDAC6 and regulates IRS1 levels and insulin signaling in the skeletal muscle during diabetes.
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Kumar, Amit and Datta, Malabika
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SKELETAL muscle , *SKELETAL muscle physiology , *WESTERN immunoblotting , *TYPE 2 diabetes , *MESSENGER RNA , *INSULIN , *INSULIN receptors - Abstract
Background: Histone deacetylases (HDACs) that catalyze removal of acetyl groups from histone proteins, are strongly associated with several diseases including diabetes, yet the precise regulatory events that control the levels and activity of the HDACs are not yet well elucidated. Methods: Levels of H19 and HDACs were evaluated in skeletal muscles of normal and diabetic db/db mice by Western Blot analysis. C2C12 cells were differentiated and transfected with either the scramble or H19 siRNA and the levels of HDACs and Prkab2, Pfkfb3, Srebf1, Socs2, Irs1 and Ppp2r5b were assessed by Western Blot analysis and qRT-PCR, respectively. Levels of H9, HDAC6 and IRS1 were evaluated in skeletal muscles of scramble/ H19 siRNA injected mice and chow/HFD-fed mice. Results: Our data show that the lncRNA H19 and HDAC6 exhibit inverse patterns of expression in the skeletal muscle of diabetic db/db mice and in C2C12 cells, H19 inhibition led to significant increase in HDAC activity and in the levels of HDAC6, both at the transcript and protein levels. This was associated with downregulation of IRS1 levels that were prevented in the presence of the HDAC inhibitor, SAHA, and HDAC6 siRNA suggesting the lncRNA H19-HDAC6 axis possibly regulates cellular IRS1 levels. Such patterns of H19, HDAC6 and IRS1 expression were also validated and confirmed in high fat diet-fed mice where as compared to normal chow-fed mice, H19 levels were significantly inhibited in the skeletal muscle of these mice and this was accompanied with elevated HDAC6 levels and decreased IRS1 levels. In-vivo inhibition of H19 led to significant increase in HDAC6 levels and this was associated with a decrease in IRS1 levels in the skeletal muscle. Conclusions: Our results suggest a critical role for the lncRNA H19-HDAC6 axis in regulating IRS1 levels in the skeletal muscle during diabetes and therefore restoring normal H19 levels might hold a therapeutic potential for the management of aberrant skeletal muscle physiology during insulin resistance and type 2 diabetes. [ABSTRACT FROM AUTHOR]
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- 2022
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217. Molecular response of Sargassum vulgare to acidification at volcanic CO2 vents: Insights from proteomic and metabolite analyses.
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Kumar, Amit, Nonnis, Simona, Castellano, Immacolata, AbdElgawad, Hamada, Beemster, Gerrit T. S., Buia, Maria Cristina, Maffioli, Elisa, Tedeschi, Gabriella, and Palumbo, Anna
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PROTEOMICS , *SARGASSUM , *OCEAN acidification , *ACIDIFICATION , *PROTEIN folding , *ACID-sensing ion channels - Abstract
Ocean acidification is impacting marine life all over the world. Understanding how species can cope with the changes in seawater carbonate chemistry represents a challenging issue. We addressed this topic using underwater CO2 vents that naturally acidify some marine areas off the island of Ischia. In the most acidified area of the vents, having a mean pH value of 6.7, comparable to far‐future predicted acidification scenarios (by 2300), the biomass is dominated by the brown alga Sargassum vulgare. The novelty of the present study is the characterization of the S. vulgare proteome together with metabolite analyses to identify the key proteins, metabolites, and pathways affected by ocean acidification. A total of 367 and 387 proteins were identified in populations grown at pH that approximates the current global average (8.1) and acidified sites, respectively. Analysis of their relative abundance revealed that 304 proteins are present in samples from both sites: 111 proteins are either higher or exclusively present under acidified conditions, whereas 120 proteins are either lower or present only under control conditions. Functionally, under acidification, a decrease in proteins related to translation and post‐translational processes and an increase of proteins involved in photosynthesis, glycolysis, oxidation–reduction processes, and protein folding were observed. In addition, small‐molecule metabolism was affected, leading to a decrease of some fatty acids and antioxidant compounds under acidification. Overall, the results obtained by proteins and metabolites analyses, integrated with previous transcriptomic, physiological, and biochemical studies, allowed us to delineate the molecular strategies adopted by S. vulgare to grow in future acidified environments, including an increase of proteins involved in energetic metabolism, oxidation–reduction processes, and protein folding at the expense of proteins involved in translation and post‐translational processes. [ABSTRACT FROM AUTHOR]
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- 2022
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218. Introduction of high-value Crocus sativus (saffron) cultivation in non-traditional regions of India through ecological modelling.
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Kumar, Amit, Devi, Mamta, Kumar, Rakesh, and Kumar, Sanjay
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SAFFRON crocus , *ECOLOGICAL models , *ECOLOGICAL niche - Abstract
Crocus sativus L. (saffron) is a globally used expensive spice. There are a few countries like Iran, Greece, Morocco, Spain, Italy, Turkey, France, Switzerland, Pakistan, China, Japan and Australia where this spice is cultivated and exported to other countries. India contributes 5% of the world's total production of which 90% is supplied only from its Jammu and Kashmir (J&K) regions. In India, the production of saffron from J&K is 3.83 tonnes whereas its annual demand is approximately 100 tonnes. In this country, there are geographical regions that have similar environmental and ecological conditions to J&K and possess the possibility of introducing this crop. Identification of such regions can be made using Ecological Niche Modelling (ENM). Therefore, 'MaxEnt' ENM was carried out using 103 environmental variables, 20 presence data and topographic parameters (elevation, slope and aspect) to find suitable regions for saffron production in unconventional areas of India. The achieved area under the curve for the model was 0.99. The precipitation and temperature were the main environmental variable influencing its cultivation. The saffron was sowed in these new modelled locations in India representing its various states such as Himachal Pradesh, Uttarakhand, Arunachal Pradesh, Sikkim, Manipur and Tamil Nadu. The quality, as well as yield of saffron produced in some of these regions, were evaluated and found at par with the saffron grown traditionally in India. Based on the promising results obtained in this work, we are expanding saffron cultivation to more modelled areas in India to meet our national demand. [ABSTRACT FROM AUTHOR]
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- 2022
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219. Revealing the Influence of Diverse Secondary Metal Cations on Redox‐Active Palladium Complexes.
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Golwankar, Riddhi R., Kumar, Amit, Day, Victor W., and Blakemore, James D.
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PALLADIUM compounds , *SCRAP metals , *LEWIS acidity , *HETEROBIMETALLIC complexes , *LEWIS acids - Abstract
Incorporation of redox‐inactive metals into redox‐active complexes and catalysts attracts attention for engendering new reactivity modes, but this strategy has not been extensively investigated beyond the first‐row of the transition metals. Here, the isolation and characterization of the first series of heterobimetallic complexes of palladium with mono‐, di‐, and tri‐valent redox‐inactive metal ions are reported. A Reinhoudt‐type heteroditopic ligand with a salen‐derived [N2,O2] binding site for Pd and a crown‐ether‐derived [O6] site has been used to prepare isolable adducts of the Lewis acidic redox‐inactive metal ions (Mn+). Comprehensive data from single‐crystal X‐ray diffraction analysis reveal distinctive trends in the structural properties of the heterobimetallic species, including an uncommon dependence of the Pd⋅⋅⋅M distance on Lewis acidity. The reorganization energy associated with reduction of the heterobimetallic species is strongly modulated by Lewis acidity, with the slowest heterogeneous electron transfer kinetics associated with the strongest incorporated Lewis acids. This hitherto unexplored reorganization energy penalty for electron transfer contrasts with prior thermodynamic studies, revealing that kinetic parameters should be considered in studies of reactivity involving heterobimetallic species. [ABSTRACT FROM AUTHOR]
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- 2022
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220. Mehar approach to solve fuzzy linear fractional minimal cost flow problems.
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Bhatia, Tanveen Kaur, Kumar, Amit, Sharma, M.K., and Appadoo, S.S.
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FRACTIONAL programming , *FUZZY numbers , *LINEAR programming , *COST - Abstract
To the best of author's knowledge, only one approach is proposed in the literature to solve fuzzy linear fractional minimal cost flow problems (minimal cost flow problems in which each known arc cost is represented either by a triangular fuzzy number or a trapezoidal fuzzy number). In this paper, the mathematical incorrect assumptions, considered in the existing approach to solve fuzzy linear fractional minimal cost flow problems, are pointed out. Also, by generalizing an existing approach for solving fuzzy linear fractional programming problems, an approach (named as Mehar approach) is proposed to solve fuzzy linear fractional minimal cost flow problems. Furthermore, two numerical examples are solved to illustrate the proposed Mehar approach. [ABSTRACT FROM AUTHOR]
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- 2022
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221. CACHING WITH TIME WINDOWS AND DELAYS.
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GUPTA, ANUPAM, KUMAR, AMIT, and PANIGRAHI, DEBMALYA
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ONLINE algorithms , *COMPUTER science , *NP-hard problems , *CACHE memory , *APPROXIMATION algorithms , *ALGORITHMS - Abstract
We consider two generalizations of the classical weighted paging problem that incorporate the notion of delayed service of page requests. The first is the (weighted) paging with time windows (PageTW) problem, which is like the classical weighted paging problem except that each page request only needs to be served before a given deadline. This problem arises in many practical applications of online caching, such as the "deadline"" I/O scheduler in the Linux kernel and video-on-demand streaming. The second, and more general, problem is the (weighted) paging with delay (PageD) problem, where the delay in serving a page request results in a penalty being added to the objective. This problem generalizes the caching problem to allow delayed service, a line of work that has recently gained traction in online algorithms (e.g., [Y. Emek, S. Kutten, and R. Wattenhofer, Proceedings of the 48th Annual ACM SIGACT Symposium on Theory of Computing, 2016, pp. 333--344; Y. Azar et al., Proceedings of the 49th Annual ACM SIGACT Symposium on Theory of Computing, 2017, pp. 551--563; Y. Azar and N. Touitou, Proceedings of the 60th IEEE Annual Symposium on Foundations of Computer Science, 2019, pp. 60--71]). We give O(log k log n)-competitive algorithms for both the PageTW and PageD problems on n pages with a cache of size k. This significantly improves on the previous best bounds of O(k) for both problems [Y. Azar et al., Proceedings of the 49th Annual ACM SIGACT Symposium on Theory of Computing, 2017, pp. 551--563]. We also consider the offline PageTW and PageD problems, for which we give O(1)-approximation algorithms and prove APX-hardness. These are the first results for the offline problems; even NP-hardness was not known before our work. At the heart of our algorithms is a novel "hitting-set"" LP relaxation of the PageTW problem that overcomes the\Omega (k) integrality gap of the natural LP for the problem. To the best of our knowledge, this is the first example of an LP-based algorithm for an online problem with delays/deadlines. [ABSTRACT FROM AUTHOR]
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- 2022
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222. Effect of exogenous additives and stress inducers on xylitol production by Debaryomyces nepalensis in batch culture.
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Kumar, Amit, Mohan, Sweta, Satpathy, Shatabdi, Pappu J., Sharon Mano, and Gummadi, Sathyanarayana N.
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SODIUM hypochlorite , *XYLITOL , *CHEMICAL industry , *HYDROGEN peroxide , *MALTOSE - Abstract
The present study investigates various strategies to improve the production of xylitol, a platform chemical, by batch cultivation of Debaryomyces nepalensis. Enhancement of xylitol production via triggerring its biosynthetic pathway in yeast cells was carried out under varied initial phosphate concentrations of the medium and by the addition of stress inducers and co‐substrates. Among the tested phosphate concentrations, the xylitol production was found to be increased by 1.62‐fold at limited initial phosphate concentration (1.5 g L−1). Similarly, among all of the studied co‐substrates, the xylitol production was found to be enhanced by adding 10% maltose at the start of fermentation. Among the different stress inducers tested, addition of hydrogen peroxide and sodium hypochlorite at low concentration (10 ppm) resulted in improved xylitol yields by 28 and 34%, respectively, when compared with the control. De facto stress inducers and nutrient limitations may be worthy of consideration to enhance the production of xylitol in batch culture. We envision that the addition of stress inducers at minimum dosage will enhance xylitol productivity. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]
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- 2022
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223. Elucidation of molecular and physiological mechanisms addressing integrated omic approaches for heavy metal stress tolerance in crops.
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Mondal, Raju, Kumar, Amit, Shabnam, Aftab Ahmad, and Chaturvedi, Ashish K.
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HEAVY metals , *PHYSIOLOGY , *HEAVY metal toxicology , *PHOTOSYSTEMS , *CROPS - Abstract
Recent industrialisation has seen an alarming increase in heavy metal pollution, raising the question of how to sustain food production in the presence of heavy metals. Several reviews have addressed the direct and indirect effects of heavy metals on crop physiological and biochemical processes. However, understanding of the physiological and molecular mechanisms requires integrating omic approaches to explore the target mechanism in general in crops, and those insights are still lacking. To date, most of the information related to omic approaches about heavy metals has been sparse and sporadic. This review, by means of examples, attempts to integrate different available proteomic, transcriptomic and genomic approaches in a nutshell along with underlying physiological and molecular mechanisms occurring in crops. Major identified transcription factors (TFs) (MYBs, WRKYs), transgenes (MT2 , Nramp6 , GSTU3 , CIPK , MYB1 and DRE), up-regulated (CAT, SODs, POD and APX), down-regulated (ATPase subunits, Rubisco subunits and photosystem I (PSI) reaction centre) proteins, and miRNA (miR397, miR398a, miR408, OsmiR601 and miR166) for major heavy metals have been summarised. It provides a mode of action of heavy metals and their fate inside the plant. It also elucidates how these omics approaches facilitate in mitigating heavy metal stress and could help in addressing crop tolerance based on these mechanisms. Identifying donors with the aid of novel omic approaches could be useful for the development of HM tolerant crops, promoting future sustainability in heavy-metal-polluted soil and water resources. [ABSTRACT FROM AUTHOR]
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- 2022
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224. Role of Glutathione S-Transferase Genes (GSTM1 and GSTT1) in cardiovascular risk factors impairment among the urban population of Chandigarh, North India.
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Rai, Abhishek, Kumar, Amit, Goyal, Deepti, Thakur, Sunil, Das, Pritam, Kaur, Dipneet, and Purkait, Pulakes
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CARDIOVASCULAR diseases risk factors , *CITY dwellers , *DIASTOLIC blood pressure , *GREEN cards , *GLUTATHIONE , *HYPERTENSION - Abstract
Oxidative stress, due to reactive oxygen species (ROS) or free radicals, can increase cardiovascular risk factors (CRFs). Lifestyle, environment, and genetics are the primary reasons for ROS generation. The role of genetics in the causation of CRFs mediated by ROS is still elusive. The present study aimed to determine the prevalence of null genotypes of oxidative stress genes (GSTM1 and GSTT1) and cardiovascular risk factors (CRFs) in an urban population. The association of GSTM1 & GSTT1 null genotypes with CRFs was also assessed in this study. A total of 40 participants (permanent residents of Chandigarh, India) were recruited. Anthropometric and physiological data were collected along with blood samples. Biochemical and molecular analysis were performed on all the collected blood samples. More than 90% of the participants had high blood pressure (HBP), 70% had obesity (OBS), and 40% had postprandial hyperglycemia (PPH). The null-genotype of GSTM1 and GSTT1 exhibited 47.50% and 7.50% of participants, respectively. GSTM1 and GSTT1 null genotypes were higher in males than females (50% vs 42.9% and 7.7% vs 7.1%). Agewise distribution showed that the absence of GSTM1 genotype was more in older participants (56.5% vs 35.3%) while GSTT1 genotype was more absent in younger participants (11.8 % vs 4.3%). Participants with null genotypes had trends of high CRFs, but only diastolic blood pressure (DBP) was significantly high. Although, mean arterial pressure (MAP) was also on the verge of significance. Odd ratio analysis showed a 2.383-fold risk of hyperglycemia in participants with either null genotypes. The present study concluded that studied participants are at greater risk of cardiovascular diseases due to high trends of CRFs. High CRFs may be related to the null genotype of GSTM1 and GSTT1 in the urban environment. Further studies with a bigger sample size are warranted to establish the results of the present study. [ABSTRACT FROM AUTHOR]
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- 2022
225. A Machine Learning-Based Method for Tuning the Control Loop of Fully Integrated Voltage Regulators.
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Govindan, Srinivasan, Kumar, Amit, Choi, Beomseok, Venkataraman, Srikrishnan, and Gope, Dipanjan
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VOLTAGE regulators , *POWER distribution networks , *MICROPROCESSORS , *ELECTRIC transients - Abstract
Fully integrated voltage regulators (FIVRs) have been introduced in the latest generation of microprocessors to improve the power efficiency and performance of processors. FIVR has a feedback control loop that regulates the output voltage in the presence of load current transients, input voltage noise, and variations or drifts in component parameters. The feedback control loop consists of a type-III op-amp compensator (CPS) with programmable resistance and capacitance (RC) values. The RC values are tuned in pre-Si and post-Si stages to achieve the desired stability and transient response. The practical op-amp CPS is nonideal, and it is difficult to model its behavior using analytical models. Hence, tuning methods based on analytical models such as the $k$ -factor method cannot be used to tune the op-amp CPS. Manual tuning of the op-amp RC values or tuning using traditional optimization methods needs either many simulations in the pre-Si stage or many measurements in the post-Si stage. The output impedance and the droop response of FIVR need to be also considered while tuning the control loop. Thus, the tuning of FIVR control loop remains a challenge with significant time and effort being spent on identifying the optimal RC values. A machine learning method based on Bayesian optimization (BO) is proposed to tune the FIVR control loop and is demonstrated to reduce the number of simulations in the pre-Si stage significantly. [ABSTRACT FROM AUTHOR]
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- 2022
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226. The Politics of GM Crops in India: Public Policy Discourse.
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Kumar, Amit
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POLICY discourse , *GOVERNMENT policy , *CROPS , *BT cotton - Published
- 2022
227. Epidemiological and Histopathological Study of Renal Cell Carcinoma: A Retrospective Study.
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KUMAR, AMIT, MAHMOOD, KHALID, UPADHYAY, ROHIT, and KUMAR, VIJOY
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NEPHRECTOMY , *RENAL cell carcinoma , *SURGICAL complications , *OCCUPATIONAL exposure , *ANGIOMYOLIPOMA , *AGE distribution , *HISTOPATHOLOGY - Abstract
Introduction: The incidence of Renal Cell Carcinomas (RCCs) has increased steadily and they have become the seventh most common histological type of cancer across the globe. Aim: To assess the profile of the patients of RCC with respect to age distribution, sex distribution, clinical presentation, site of tumour, risk factors, staging, histopathological examination, and operative complications. Materials and Methods: A retrospective descriptive study was conducted in Department of Urology, Indira Gandhi Institute of Sciences, Patna, Bihar, India, from January 2019 to June 2020, that included patients with RCC. The pathology specimens and reports of patients with RCC who underwent laparoscopic, open, cytoreductive, and partial nephrectomy were reviewed. Data related to demographic characteristics, site of tumour, risk factors, co-morbidities, clinical features, histopathology, tumour grade and stage, type of surgery, intra-and postoperative complications, and Fuhrman nuclear grading system were recorded. Results: Total 60 patients diagnosed with RCC were included in this study. Of these, majority of patients were men (n=44). Majority of patients belonged to the age group of =60 years (n=39). Smoking (n=30), hypertension (n=30), obesity (n=20), and occupational exposure (n=8) were major risk factors associated with RCC. Haematuria (n=36), flank pain (n=24), hematuria and lump, with flank pain (n=18), and weight loss (n=18) were the most common clinical features in patients with RCC. According to the histopathologic type, 30 (50.0%) patients had clear cell RCC, 18 (30.0%) had papillary RCC, 8 (13.3%) had chromophobe RCC and the other four (6.7%) had cystic neoplasm, urothelial, angiomyolipoma, or sarcomatoid. Twenty-four patients underwent laparoscopic nephrectomy while 31 patients underwent open nephrectomy. Cytoreductive and partial nephrectomy was performed in three and two patients, respectively. Conclusion: The present study findings suggest that age has an impact on development of RCC. Also, intraoperative and postoperative complications were more common among patients who underwent open nephrectomy. [ABSTRACT FROM AUTHOR]
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- 2022
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228. Simultaneous hydrogen production and photocatalytic pollutant removal: a review.
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Kumar, Amit, Sharma, Pankaj, Sharma, Gaurav, Dhiman, Pooja, Mola, Genene Tessema, Farghali, Mohamed, Rashwan, Ahmed K., Nasr, Mahmoud, Osman, Ahmed I., and Wang, Tongtong
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Pollution and the rising energy demand are two major society issues, requiring urgent solutions. Here, we review the simultaneous production of hydrogen and removal of pollutants, with a focus on mechanisms, synthesis of photocatalysts, and applications. Remarkably, this method utilizes organic pollutants as sacrificial agents for photocatalytic hydrogen production, thus both reducing pollution and producing energy. Metal-doped, cocatalyst-loaded, organic and inorganic composite, heterostructure and heterojunction photocatalysts are described. We present applications to the removal of antibiotics and organic dyes. Pollutant degradation rates range from 5.3 to 100%, with hydrogen evolution of 13.7–2724.89 μmol·g–1h–1. [ABSTRACT FROM AUTHOR]
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- 2024
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229. Targeting OsNIP3;1 via CRISPR/Cas9: A strategy for minimizing arsenic accumulation and boosting rice resilience.
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Singh, Puja, Kumar, Amit, Singh, Twinkle, Anto, Sonik, Indoliya, Yuvraj, Tiwari, Poonam, Behera, Soumit Kumar, and Chakrabarty, Debasis
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CRISPRS , *ARSENIC , *GENOME editing , *PHOTOSYNTHETIC pigments , *GENE families - Abstract
Arsenic (As) contamination in rice poses a significant threat to human health due to its toxicity and widespread consumption. Identifying and manipulating key genes governing As accumulation in rice is crucial for reducing this threat. The large NIP gene family of aquaporins in rice presents a promising target due to functional redundancy, potentially allowing for gene manipulation without compromising plant growth. This study aimed to utilize genome editing to generate knock-out (KO) lines of genes of NIP family (OsLsi1, OsNIP3;1) and an anion transporter family (OsLsi2), in order to assess their impact on As accumulation and stress tolerance in rice. KO lines were created using CRISPR/Cas9 technology, and the As accumulation patterns, physiological performance, and grain yield were compared against wild-type (WT) under As-treated conditions. KO lines exhibited significantly reduced As accumulation in grain compared to WT. Notably, Osnip3;1 KO line displayed reduced As in xylem sap (71–74%) and grain (32–46%) upon treatment. Additionally, these lines demonstrated improved silicon (23%) uptake, photosynthetic pigment concentrations (Chl a: 77%; Chl b: 79%, Total Chl: 79% & Carotenoid: 49%) overall physiological and agronomical performance under As stress compared to WT. This study successfully utilized genome editing for the first time to identify OsNIP3;1 as a potential target for manipulating As accumulation in rice without compromising grain yield or plant vigor. [Display omitted] • Study focuses on targeting various As transporters - OsLsi1, OsLsi2 and OsNIP3;1 by genome editing. • Knock-out (KO) plants showed reduced As content in various parts of rice including grain. • OsNIP3;1 edited lines (KO Osnip3;1) showed reduced arsenic content in xylem sap by 71-74%. • Enhanced physiological and agronomic traits were observed in Osnip3;1 under As stress. [ABSTRACT FROM AUTHOR]
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- 2024
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230. Microstructure and mechanical properties of a dissimilar metal welded joint of Inconel 617 and P92 steel with Inconel 82 buttering layer for AUSC boiler application.
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Kumar, Amit, Sirohi, Sachin, Singh, Manohar, Fydrych, Dariusz, and Pandey, Chandan
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MECHANICAL properties of metals , *BUTTER , *DISSIMILAR welding , *GAS tungsten arc welding , *INCONEL , *NOTCHED bar testing , *FILLER metal - Abstract
The application of the novel dissimilar metal welded (DMW) joint, utilizing Inconel 617 and P92 steel, was showcased in the advanced ultra-supercritical (AUSC) boiler. The work has been performed to investigate the effect of Inconel 82 (ERNiCr-3) buttering layer on microstructure and mechanical properties (high-temperature tensile strength, impact strength and microhardness) of gas tungsten arc welded (GTAW) dissimilar joint between Inconel 617 and P92 steel fabricated using the Inconel 617 (ERNiCrCoMo-1) filler. For optical microscopy and scanning electron microscopy (SEM), samples were machined along a transverse direction which comprised the butter layer, weld metal, and heat-affected zone of both sides. The energy-dispersive X-ray spectroscopy (EDS) was used to map the interface of the buttering layer and weld metal and butter layer and P92 steel. The high-temperature tensile testing and Charpy impact testing at room temperature were conducted for the integrity assessment of the welded joint. The examination of microstructure and hardness revealed that the buttering layer of Inconel 82 filler successfully mitigated a significant portion of the brittle martensitic microstructure from the coarse-grained heat-affected zone (CGHAZ), along with hardness peaks on the side of P92 steel. The conventional method of DMW joint fabrication, without the use of a buttering layer, has been demonstrated to be less favourable compared to the new fabrication method, which incorporates a buttering layer. The TiC/NbC carbides were identified in the Inconel 82 buttering layer, whereas M 23 C 6 and Mo 6 C carbides were found in the Inconel 617 filler weld. Near the interface of the Inconel 82 buttering layer and P92 steel, the formation of peninsula and island structures, as well as Type I and Type II boundaries, were confirmed. Additionally, element diffusion of Ni, Cr, and Fe was observed. The tensile test results indicated an ultimate tensile strength of 620 ± 4 MPa and % elongation of 19 ± 4 % at room temperature, with fracture occurring in the buttering layer near the interface of the buttering layer and P92 steel. At temperatures of 550 °C and 650 °C, the ultimate tensile strength decreased to 448 MPa and 326 MPa, respectively, with fractures occurring in the P92 steel, irrespective of temperature. The hardness of the Inconel 82 buttering layer and Inconel 617 filler weld were 219 ± 10 HV and 248 ± 11 HV, respectively. The Charpy impact toughness of the Inconel 82 buttering layer and Inconel 617 filler weld were 138 ± 6 J and 115 ± 4 J, respectively. The study comprehensively investigates and discussed the correlations between microstructure and mechanical properties. • A dissimilar welded joint of buttered P92 steel and Alloy 617 was fabricated using the GTAW process. • The structural integrity of the welded joint was tested using high temperature tensile tests, hardness tests and Charpy impact tests. • A detailed investigation of the dissimilar weldments was performed using the SEM/EDS and optical microscopy. • A relation between microstructure and mechanical properties was investigated. [ABSTRACT FROM AUTHOR]
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- 2024
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231. Atmospheric water extraction based on solar air heater encapsulated with phase change material: An experimental investigation.
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Agrawal, Anshu and Kumar, Amit
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SOLAR air heaters , *PHASE change materials , *BIOPHYSICAL economics , *SUSTAINABLE buildings , *HEAT exchangers , *SILICA gel , *WATER heaters - Abstract
Amidst worsening water scarcity in the urban region, exploring alternative water sources is crucial. Atmospheric water extraction (AWE) technology emerges as a cost-effective and efficient remedy for the escalating issue of water scarcity. The objective of this research is to experimentally explore a novel AWE system that incorporates phase change material (PCM). This system is designed to facilitate uninterrupted water generation, even when there is no solar energy. It comprises of a solar air heater based on both-sides open evacuated tube collector having an area of 4.86 m2, which is encapsulated with acetamide-PCM. Additionally, it incorporates a silica gel filled desiccant bed and an air-cooled heat exchanger for vapor condensation. The system is investigated for two different desiccant bed weights of 15 kg (case 1) and 20 kg (case 2), respectively. The system's effectiveness is examined based on rate of adsorption, rate of regeneration, thermal, overall & exergy efficiency. The economic, environmental & enviro-economic analysis is also presented to ensure the system's sustainability & feasibility for its practical use. The results demonstrate that for case 2 the system extracts 4.1 L/day (0.843 L/m2/day) fresh water with 12.65%, 10.48% and 5.65% thermal, overall and exergy efficiency, respectively, for 20 kg desiccant bed weight. The fresh water cost is 0.12 $/L with 2 years & 1 month of payback time and 4 years & 7 months of energy payback period. The environmental & enviro-economic analysis ensures the system's eco-friendliness. Additionally, rigorous quality testing of the extracted water is carried out to affirm its suitability for safe consumption. • PCM encapsulated solar air heater for atmospheric water extraction. • Both sides open evacuated tube collector produces hot air of 130.10 °C. • Maximum water extracted is 4.1 L/day using air-cooled heat exchanger. • Thermal & exergy efficiency reported is 12.65 % & 5.65 %, respectively. • Water generation cost is 0.12 $/L, with system payback time of 2 years & 1 month. [ABSTRACT FROM AUTHOR]
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- 2024
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232. Ensuring carbon neutrality via algae-based wastewater treatment systems: Progress and future perspectives.
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Kumar, Amit, Mishra, Saurabh, Singh, Nitin Kumar, Yadav, Manish, Padhiyar, Hirendrasinh, Christian, Johnson, and Kumar, Rupesh
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WASTEWATER treatment , *CARBON offsetting , *LIFE cycle costing , *MACHINE learning , *GREENHOUSE gas mitigation , *POLLUTION remediation - Abstract
The emergence of algal biorefineries has garnered considerable attention to researchers owing to their potential to ensure carbon neutrality via mitigation of atmospheric greenhouse gases. Algae-derived biofuels, characterized by their carbon-neutral nature, stand poised to play a pivotal role in advancing sustainable development initiatives aimed at enhancing environmental and societal well-being. In this context, algae-based wastewater treatment systems are greatly appreciated for their efficacy in nutrient removal and simultaneous bioenergy generation. These systems leverage the growth of algae species on wastewater nutrients—including carbon, nitrogen, and phosphorus—alongside carbon dioxide, thus facilitating a multifaceted approach to pollution remediation. This review seeks to delve into the realization of carbon neutrality through algae-mediated wastewater treatment approaches. Through a comprehensive analysis, this review scrutinizes the trajectory of algae-based wastewater treatment via bibliometric analysis. It subsequently examines the case studies and empirical insights pertaining to algae cultivation, treatment performance analysis, cost and life cycle analyses, and the implementation of optimization methodologies rooted in artificial intelligence and machine learning algorithms for algae-based wastewater treatment systems. By synthesizing these diverse perspectives, this study aims to offer valuable insights for the development of future engineering applications predicated on an in-depth understanding of carbon neutrality within the framework of circular economy paradigms. • Utilization of algae in wastewater treatment helps in acheiving carbon neutrality. • Research trend of algal wastewater treatment is analyzed via bibliometric analysis. • Chlorella vulgaris is the most investigated species in wastewater treatment system. • Binary culture approach has shown significant benefits over conventional systems. • AI and ML integration in algal system has potential benefits in carbon neutrality. [ABSTRACT FROM AUTHOR]
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- 2024
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233. Thermal analysis of humidification–dehumidification desalination system based on evacuated tube solar air heater.
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Tiwari, Abhishek and Kumar, Amit
- Abstract
Desalination, which converts saline water into freshwater, has been proposed as a possible alternative to address the worldwide freshwater scarcity problem. The humidification–dehumidification (H–DH) desalination technique can provide appropriate quantity of freshwater to the population residing in water-stressed regions. The aim of the current study is to investigate the solar H–DH desalination system performance which consists of a solar air heater based on double-ends open evacuated tube collector, a packed bed humidifier, and a dehumidifier. The packing material used in humidifier is aspen pads. The performance is assessed based on system overall efficacy, gained output ratio (GOR), yield, and efficacy of humidifier and dehumidifier at three distinct process air flow rates. The average overall system efficacy, yield, and GOR are 11.97%, 4.1 kg day-1, and 0.84, respectively, for open-loop system. The closed-loop system reports better performance at low mass flow rate. The average overall system efficiency, daily yield, and GOR at 100 kg h−1 are 32.48%, 11.9 kg day-1, and 2.44, respectively, for a closed-loop system. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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234. Comparative analysis of Benchmark and Aeon Blue Technologies for sustainable eFuel production: Integrating Direct Air Capture and Green Hydrogen approaches.
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Kumar, Amit, Tiwari, Arun Kumar, and Cearnaigh, Deóis Ua
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SUSTAINABILITY , *GREEN fuels , *CHEMICAL processes , *CARBON sequestration , *HYDROGEN production , *ENERGY consumption , *METHANOL as fuel - Abstract
[Display omitted] • The pH-swing cold capture chloralkali process improves energy efficiency threefold over the benchmark process. • Integrating pH-swing cold capture chloralkali in eFuel synthesis moves most of the energy consumption to the electrolyzer. • We attain ∼ 76 % carbon capture efficiency and 79.5 % overall process efficiency. Renewable Fuels of Non-Biological Origin (RFNBOs, a.ka. "eFuels") are drop-in replacements for fossil fuels in the "hard-to-abate" sectors, and utilise existing distribution and storage infrastructure, but suffer from low synthetic efficiency. In particular, the low efficiency and high energy consumption of hydrogen synthesis by freshwater electrolysis remains a problem to be addressed. In the current study, we explore the potential of saltwater electrolysis (chloralkali) for the synthesis of eFuels generally, and specifically eMethanol. The study explores the use of chlorinated water in carbonate-loop pH-swing "cold capture" of carbon dioxide, and the resulting synergetic integration of the chloralkali process in eFuel syntheses. Doing so eliminates the high energy consumption of the calciner and the slaker of the benchmarked carbonate-loop thermal-swing method. It is replaced with a spontaneous chemical process in which chlorine is neutralized in the presence of carbonates. This allows the simultaneous solution of "The Chlorine Problem" of saltwater electrolysis, and a lower overall energy consumption of direct air capture when combined with green hydrogen synthesis. The only limitation on the comparison is that a large amount of carbon dioxide is over-captured when using chloralkali. That is, the ratio of hydrogen generated to carbon dioxide captured is fixed by the stoichiometry of chloralkali and not that of the eFuel. This results in an excess of carbon captured and thus a carbon-negative eFuel. We examine one configuration of secondary revenue and use it to inform the marginal cost of CO 2 capture. In the system proposed by Aeon Blue Technologies (ABT), carbon dioxide is absorbed into caustic according to the standard method. Hydrogen gas is produced in a standard chloralkali electrolyzer, along with caustic for the contactor, and chlorine. Water oxidation by chlorine gives the strong acid, hydrochloric acid, and the weak acid, hypochlorous acid, which react directly with wet carbonate to release CO 2. H 2 and CO 2 react in a methanol reactor to produce eFuel. H 2 is the limiting reagent for eFuel synthesis, giving an excess of cold captured CO 2. Thus, the current study underscores significant advancements in renewable fuel synthesis, particularly eMethanol, and evaluates the carbon capture and energy efficiency of a novel method. The simulation indicates that the marginal energy cost for a tonne of CO 2 is ∼ 184kWh. This gives ∼ 76 % theoretical carbon capture efficiency and an overall process efficiency of 79.5 % (approximately a threefold improvement over the benchmark). The authors are unaware of a comparable method. The overall system yields a tonne of carbon-neutral e-methanol (eMeOH) while capturing an additional 3 tonnes of carbon dioxide, which means the modelled process captures over 300 % more carbon dioxide than is released upon combustion of the eFuel. In summary, this research contributes valuable insights into carbon-negative eFuel production, representing a significant scientific step in sustainable fuel production. [ABSTRACT FROM AUTHOR]
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- 2024
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235. Recent progress in ZnCr and NiCr layered double hydroxides and based photocatalysts for water treatment and clean energy production.
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Rana, Sahil, Kumar, Amit, Lai, Chin Wei, Sharma, Gaurav, and Dhiman, Pooja
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WATER purification , *SUSTAINABILITY , *LAYERED double hydroxides , *PHOTOCATALYSTS , *GREEN business - Abstract
In pursuit of advancing photocatalysts for superior performance in water treatment and clean energy generation, researchers are increasingly focusing on layered double hydroxides (LDHs) which have garnered significant attention due to their customizable properties, morphologies, distinctive 2D layered structure and flexible options for modifying anions and cations. No review has previously delved specifically into ZnCr and NiCr LDH-based photocatalysts and therefore, this review highlights the recent surge in ZnCr and NiCr-based LDHs as potential photocatalysts for their applications in water purification and renewable energy generation. The structural and fundamental characteristics of layered double hydroxides and especially ZnCr-LDHs and NiCr-LDHs are outlined. Further, the various synthesis techniques for the preparation of ZnCr-LDHs, NiCr-LDHs and their composite and heterostructure materials have been briefly discussed. The applicability of ZnCr-LDH and NiCr-LDH based photocatalysts in tackling significant issues in water treatment and sustainable energy generation is the main emphasis of this review. It focuses on photocatalytic degradation of organic pollutants in wastewater, elucidating the principles and advancements for enhancing the efficiency of these materials. It also explores their role in H 2 production through water splitting, conversion of CO 2 into valuable fuels and NH 3 synthesis from N 2 , shedding light on their potential for clean energy solutions. The insights presented herein offer valuable guidance for researchers working towards sustainable solutions for environmental remediation and renewable energy generation. [Display omitted] • Fundamentals and properties of Layered Double Hydroxides (LDHs). • ZnCr and NiCr LDHs as photocatalysts-Properties and Performance. • Water treatment and clean energy production-Mechanism and issues. • ZnCr and NiCr LDH based water treatment & clean energy production. • The challenges and future development direction for sustainable use are discussed. [ABSTRACT FROM AUTHOR]
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- 2024
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236. Assessment of machine learning models to predict daily streamflow in a semiarid river catchment.
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Kumar, Amit, Gaurav, Kumar, Singh, Abhilash, and Yaseen, Zaher Mundher
- Abstract
In this study, we employ explainable machine learning (ML) models to predict daily streamflow (Qflow\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$Q_{\rm{flow}}$$\end{document}) by leveraging hydro-meteorological parameters. The predictive matrix incorporates crucial factors such as daily rainfall, temperature, relative humidity, solar radiation, wind speed, and the one-day lag value of Qflow\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$Q_{\rm{flow}}$$\end{document}. Notably, among these parameters, the one-day lag value of Qflow\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$Q_{\rm{flow}}$$\end{document}, along with rainfall, solar radiation, temperature, and relative humidity emerge as highly influential predictors. We apply various ML models, including bagging ensemble learning, boosting ensemble learning, Gaussian process regression (GPR), and automated machine learning (Auto ML). Following a rigorous evaluation, the bagging ensemble learning model stands out as the most effective with a correlation coefficient (
R = 0.80) and root-mean-square error (RMSE = 218). Further, we compare the Qflow\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$Q_{\rm{flow}}$$\end{document} predicted using ML models with a process-based hydrological model (SWAT) that was executed using a similar set of climatic variables as the input parameters. In our case, the predictive strength of the ML model (R = 0.80; RMSE = 218) to estimate (Qflow\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$Q_{\rm{flow}}$$\end{document}) is greater than the SWAT (R = 0.82; RMSE = 281). In conclusion, by emphasizing the importance of explainable ML models and highlighting the significance of specific hydro-meteorological parameters, our study contributes to advancing the field of hydrology and water resource management. [ABSTRACT FROM AUTHOR]- Published
- 2024
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237. Revealing the Novel Genetic Resources for Blast Resistance in Diverse Rice Landraces of North-Eastern Hills of Himalayas.
- Author
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Raj, Riya, Kumar, Amit, C, Balakrishnan, S, Philanim W., Touthang, Letngam, Das, S. P., Rai, Mayank, Verma, Veerendra Kumar, and Mishra, Vinay Kumar
- Abstract
Rice blast disease is one of the most disastrous diseases causing significant losses to the crop. In the humid weather conditions of north-eastern Himalayan region, the situation is highly devastating as the climate is very favorable to the fungus
Magnaporthe oryzae . Development of resistant rice varieties is the most effective, economical, and environment-friendly way to control this disease. The study aimed to identify novel sources of resistant donor using agro-morphological and gene-based markers for their utilization in development of blast-resistant varieties with high yield potential. Phenotypic evaluation has classified the hundred landraces into resistant (13), moderately resistant (43), moderately susceptible (24), and susceptible (20). Fifty-nine genotypes were found to carry genes responsible for blast resistance, either singly or in combination. The genotype MN-62 was found to have a blast score of zero in field screening. The genetic frequencies of the major blast resistance genes ranged from 28 to 97%. The cluster analysis grouped the landraces into three major groups. Additionally, the association between blast genes was computed with blast score using a general linear model (GLM) and mixed linear model (MLM), revealing that the markers AP4007, AP56595, C1454, and RM208 were found to be associated with the trait. The landraces with six blast R-genes like Nungshang Phou, Ratkhara, Anandhi, RCPL 1–44, Ching Phou Khong Nombi, MN-31, Rona Yang, and RCPL-128 were also superior for agro-morphological traits. Similarly, the landraces MN-62, Tara Bali, Rato Bhan Joha, MN-47, RCPL 1–411, and CAU-R1 were promising regarding yield and blast resistance. The resistant lines with various combinations of blast resistance genes can be utilized for introgression of genes into the commercial varieties for durable resistance using marker-assisted backcrossing. [ABSTRACT FROM AUTHOR]- Published
- 2024
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- View/download PDF
238. Election Forecasting: Improving accuracy.
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Arjumand, Tahera, Kumar, Amit, Aneaus, Sheikh, Induja, M. S., Mullasseri, Sileesh, Hans, Aradhana, Manjari, K. Sri, and Jadav, Ravindra
- Published
- 2024
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239. Probiotic Dark Chocolate: Improves gut microflora.
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Arjumand, Tahera, Kumar, Amit, Aneaus, Sheikh, Induja, M. S., Mullasseri, Sileesh, Hans, Aradhana, Manjari, K. Sri, and Jadav, Ravindra
- Published
- 2024
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240. Improving Meat Patties: With dietary fibre and antioxidants.
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Arjumand, Tahera, Kumar, Amit, Aneaus, Sheikh, Induja, M. S., Mullasseri, Sileesh, Hans, Aradhana, Manjari, K. Sri, and Jadav, Ravindra
- Published
- 2024
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241. Treating Cadmium Contamination: Using agricultural waste.
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Arjumand, Tahera, Kumar, Amit, Aneaus, Sheikh, Induja, M. S., Mullasseri, Sileesh, Hans, Aradhana, Manjari, K. Sri, and Jadav, Ravindra
- Published
- 2024
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242. Gastrointestinal Parasites: Ungulates in Ladakh.
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Arjumand, Tahera, Kumar, Amit, Aneaus, Sheikh, Induja, M. S., Mullasseri, Sileesh, Hans, Aradhana, Manjari, K. Sri, and Jadav, Ravindra
- Published
- 2024
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243. Extraction, physicochemical and structural characterisation of palm grass leaf fibres for sustainable and cleaner production of textile and allied cellulosic applications.
- Author
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Kumar, Amit, Dutta, Dipanka, Kalita, Dipul, Majumdar, Bijan, Saikia, Siddhartha Proteem, and Banik, Dipanwita
- Subjects
- *
NATURAL fibers , *SUSTAINABILITY , *LEAF fibers , *GREEN business , *SUSTAINABLE development , *CENCHRUS purpureus , *SCANNING electron microscopes , *PALMS - Abstract
Natural fibres are in great demand as a clean and green material as reinforcement in sustainable and environment-friendly biodegradable composites. The study aimed to extract palm grass leaf fibres through water retting, a cleaner and greener approach compared with the use of 5–10% NaOH. The physicochemical characterisation was done by SEM, optical microscopy, FT-IR, XRD, TGA, bundle strength, moisture content and standard biochemical tests for cellulose, hemicellulose, lignin and ash. New natural fibres extracted from Curculigo capitulata by water retting showed a smooth surface of uniaxial fibres under SEM and optical microscope compared to eroded surfaces of chemically extracted fibres. Both the fibres extracted by water retting and with 5% NaOH showed nearly similar crystallinity index (84–85%) and size (2.44nm), whereas the former contained 64% cellulose with bundle strength 154MPa compared to 72% and 219.11MPa with the latter. While using 10% (NaOH) showed cellulose 82.29 ± 0.63%, crystallinity index 87.43%, and bundle strength 256.46 ± 15.81MPa. Approximately similar lignin content (20.30 ± 0.91–21.66 ± 1.18%) and mass degradation (%) were obtained in water-retted and 5%–7.5% NaOH extracted fibres. FT-IR spectra showed the characteristic bands at 3421cm−1 for O–H stretching and 2917cm−1 for alkyl C–H stretching in cellulose; at 1630cm1 for C C stretching in lignin. All the extracted fibres showed industrial potential similar to successful natural fibres for fine rope, yarn, handmade paper, and fabrics aiming for a circular bioeconomy. [Display omitted] • New natural fibres were extracted for the first time from Palm grass leaves (Curculigo capitulata), a bio-waste by biological and chemical methods • A sustainable cleaner and greener biological retting resulted smooth surface of uniaxial fibres • Physicochemical characterization was done with SEM, FT-IR, TGA, contents of lignin, cellulose, hemicellulose and bundle strength • New natural fibres showed similarity with commercial natural fibres used in biodegradable fabrics and as reinforcement in green composites [ABSTRACT FROM AUTHOR]
- Published
- 2024
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- View/download PDF
244. Current progress in heterojunctions based on Nb2O5 for photocatalytic water treatment and energy applications.
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Kumar, Amit, Rana, Sahil, Dhiman, Pooja, Sharma, Gaurav, and Stadler, Florian J.
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- *
WATER purification , *PHOTOCATALYSIS , *HETEROJUNCTIONS , *SURFACE charges , *PHOTOCATALYSTS , *AUTOMATIC control systems , *SURFACE reactions - Abstract
[Display omitted] • Overview of fundamentals of Nb 2 O 5 as photocatalyst-structure and properties. • Heterojunction photocatalysts -Z and S scheme- charge transfer routes. • Recent advances in Nb 2 O 5 based heterojunctions for photocatalytic applications. • Strategies for improving the photocatalytic performance Nb 2 O 5 based heterojunctions. Significant advancements in the field of photocatalysis in recent years have highlighted the heterojunctions based on Nb 2 O 5 as a focal point of research. This comprehensive review diligently analyses the progress in Nb 2 O 5 -based heterojunctions for their application in photocatalysis, focusing on synthesis, characteristics and their pivotal role in addressing crucial energy and environmental challenges. The review emphasizes the fundamental principles of photocatalysis in pollutant removal and H 2 generation, elucidating key processes such as light absorption, charge generation and surface reactions. The different types of heterojunctions, their basic principles and role in enhancing the charge separation and overall photocatlytic performance have been discussed. The recent advances in Nb 2 O 5 -based heterojunctions are extensively discussed for the photocatalytic applications such as pollutants removal and H 2 evolution. Furthermore, the review delves into strategies employed to enhance the photocatalytic activity of Nb 2 O 5 -based heterojunctions such as doping, oxygen vacancies modification, morphological engineering and atomic control, as well as loading with support materials. Each strategy is explained, emphasizing its impact on charge separation and overall efficiency. The review concludes by highlighting existing challenges and providing insights into potential future directions that integrates synthetic processes, novel methods for photoelectric characterization, and an in-depth understanding of the local structure of Nb 2 O 5. This review serves as a valuable resource for researchers in the field, offering a comprehensive overview of the state-of-the-art in Nb 2 O 5 -based heterojunctions for advanced photocatalytic applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
245. Dynamical behaviors and abundant optical soliton solutions of the cold bosonic atoms in a zig-zag optical lattice model using two integral schemes.
- Author
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Kumar, Sachin and Kumar, Amit
- Abstract
In this present paper, we obtain hyperbolic, exponential, trigonometric function, other soliton solutions, and their combinations for the cold bosonic atoms in a zig-zag optical lattice model based on two efficient methods, such as the generalized Riccati equation mapping (GREM) method and generalized Kudryashov (GK) method. The used techniques are very reliable and effective tools and provide numerous exact soliton solutions of the nonlinear PDE. The zig-zag optical lattice model, widely used to represent the nonlinear wave and the soliton dynamics in fluid dynamics and plasma physics, is examined in this article to obtain exact optical soliton solutions and study their physical properties. For this, we first convert a partial differential equation (PDE) into an ordinary differential equation (ODE) by employing wave transformation and then split the equation into imaginary and real parts. The derived optical soliton solutions are illustrated graphically using Mathematica software to distinguish constant parameter values. Consequently, bell-shape, anti-bell-shape, traveling wave, periodic, mix periodic, singular soliton, and some new types of solitons demonstrate to validate these acquired outcomes with physical phenomena and make the results worthy. Furthermore, the 3D, 2D, and contour graphs are sketched to assign suitable constant parameters to illustrate the physical phenomena of the obtained solutions. The accomplished soliton solutions indicate that the applied computational system is a direct, reliable, productive, and more complex physical phenomenon. Symbolic computation is used in the software package Mathematica to obtain the various soliton solutions and different dynamical behavior of the newly formed solutions • Cold bosonic atoms (CBA) in a zig-zag optical lattice model are studied using two mathematical methods, namely: generalized Riccati equation mapping method and generalized Kudryashov method. • We obtain various optical soliton solutions and different dynamical behaviors using two efficient mathematical methods. • Computerized symbolic computation is used to obtain various soliton solutions and different dynamical behavior of the newly formed solutions. • Exact optical soliton solutions exhibit physical features such as a bell-shaped soliton, bright and dark multi-solitons, singular solitons, and various solitary waves. • In addition, the 3D, 2D, and contour graphs are used to assign appropriate constant parameters to demonstrate the physical phenomena of the derived solutions. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
246. Influence of PWHT Parameters on the Mechanical Properties and Microstructural Behavior of Multi-Pass GTAW Joints of P92 Steel.
- Author
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Sirohi, Sachin, Kumar, Amit, Soni, Shiva, Dak, Gaurav, Kumar, Sanjeev, Świerczyńska, Aleksandra, Rogalski, Grzegorz, Fydrych, Dariusz, and Pandey, Chandan
- Subjects
- *
GAS tungsten arc welding , *TUNGSTEN alloys , *FUSION zone (Welding) , *WELDED joints , *HEAT treatment , *STEEL - Abstract
The 9% Cr steels were developed for ultra-supercritical (USC) power plants to meet the requirements of high operating temperature and pressure. These steels are produced to operate at high temperatures where impact toughness is not a concern; however, it becomes important for the welded joints to have good impact toughness at room temperature for manufacturing. The present work investigates the effect of the post-weld heat treatment (PWHT) parameters, i.e., temperature and time, on the impact toughness of multi-pass gas tungsten arc welded (GTAW) joints of ferritic/martensitic grade P92 steel. The microstructural evolution in welded joints given varying post-weld temperatures and times was studied. The lath martensitic structure of the weld metal for the as-welded joints resulted in high hardness and low impact toughness. The weld fusion zone toughness was 12 J, which was lower than the minimum specified values of 41 J (ASME standards) and 47 J (EN ISO 3580:2017). The PWHT temperature and time were found to have a significant effect on the impact toughness of the weld metal. A drastic increase in the impact toughness of the weld metal was noticed, which was attributed to lath break-up, reduction in dislocation density and reduction in solid solution hardening. The maximum impact toughness of 124 J was measured for PWHT temperature and time of 760 °C and 120 min, respectively. The effect of PWHT parameters on tensile strength was also investigated, and test results showed that the joint was safe for USC boiler application as it failed from the region of the P92 base metal. The variation in microstructural evolution along the weldments resulted in hardness variation. PWHT led to homogeneity in microstructure and, ultimately, reduction in hardness value. According to the study, the optimum temperature and time for PWHT of a GTAW joint of P92 steel were found to be 760 °C and 120 min, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
247. Quad‐band circularly polarized super‐wideband MIMO antenna for wireless applications.
- Author
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Kumar, Amit, Saxena, Gaurav, Kumar, Preetam, Awasthi, Yogendra Kumar, Jain, Priyanka, Singhwal, Sumer Singh, and Ranjan, Prashant
- Subjects
- *
ANTENNAS (Electronics) , *CIRCULAR polarization , *CELL size , *WIRELESS LANs - Abstract
In this article, a Super‐wideband (2.6–22 GHz) two‐elements multiple‐input‐multiple‐output antenna (MIMO) is presented with a dimension of 49 × 54.5 × 1.6 mm3 on an FR‐4 substrate. The antenna is also exhibited dual circular polarization (RHCP and LHCP) simultaneously at two separate ports at four frequencies of 5.2, 11.5, 14.66, and 16.75 GHz, which are extensively utilized for WLAN, X, and Ku‐band applications. Four EBG cells of various sizes have been installed across the feed line to maintain the antenna's efficiency and control the specific absorption rate (SAR). The antenna has a minimum isolation of 17 dB (20 dB for the important portion) in Super‐wideband (SWB) and excellent diversity performance. Simulated results of antenna‐like return loss, isolation, and diversity parameters have also been verified experimentally, which are in the acceptable range. Also, the calculated maximum SAR at 10 g is 1.095 W/kg with the head voxel model at 3.5 GHz. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
248. Multicomponent Synthesis of 4-Aryl-1,4-Dihydro-Oxochromeno[3,2-b] Oxoindeno[6,5-e]Pyridine.
- Author
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Kumar, Amit, Mahiya, Kuldeep, Prasad, Ashok K., and Singh, Sunil K.
- Subjects
- *
AROMATIC aldehydes , *ACETALDEHYDE , *PYRIDINE , *ETHYLENE glycol , *ACETIC acid , *IMIDAZOPYRIDINES - Abstract
One pot multi-component strategy has been developed for the synthesis of a small library of nineteen 4-aryl-1,4-dihydro-oxochromeno[3,2-b]oxoindeno[6,5-e]pyridine by the condensation of 4-aminocoumarin, aromatic aldehyde and indane-1,3-dione in acetic acid:ethylene glycol (5:1) in good yields along with the formation of di-(4-aminocoumarin-3-yl)arylmethane as by product in three cases. The use of microwave irradiation for the condensation of 4-aminocoumarin, aromatic aldehyde and indane-1,3-dione in acetic acid and ethylene glycol at 200 W and at 120 °C led to the selective formation of 4-aryl-1,4-dihydro-oxochromeno[3,2-b]oxoindeno[6,5-e] pyridine in excellent yields. Interestingly, the side product di-(4-aminocoumarin-3-yl)arylmethane could be converted exclusively to 4-(4'-nitrophenyl)-1,4-dihydro-di(oxochromeno[3,2-b:5,6-e])pyridine on microwave irradiation under identical condition. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
249. Electromagnetic Weibel instability in spatial anisotropic electron–ion plasmas.
- Author
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Kumar, Amit, Gupta, Ruby, and Sharma, Jyotsna
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- *
PLASMA instabilities , *WAVENUMBER , *THERMAL electrons , *ELECTROMAGNETIC waves , *ELECTRON plasma - Abstract
The Weibel instability due to temperature anisotropy of electrons and ions in a plasma in the presence of cold and warm ions is reported. Numerical calculations of the normalized growth rate are carried out when the frequency of electromagnetic waves is greater than or less than the thermal velocity of electrons for typical existing plasma parameters. The normalized growth rate increases with an increasing normalized wave number, and after attaining maxima, it decreases due to thermal effects. Therefore, a parabolic plot is obtained for the growth rate. The threshold values of the growth rate depend on the anisotropy parameters. On increasing the value of the temperature anisotropy ratio of either plasma component, the observed growth rate increases. There is a considerable and contrasting effect of the presence of cold and warm ions on the growth rate of the Weibel instability in the plasma. The addition of cold ions stabilizes the instability and reduces the maximum growth rate values, while the addition of warm ions to the plasma increases the instability with a considerable decrease in the domain of instability. Our theoretical investigations of the effect of temperature anisotropy on the growth rate of the Weibel instability are in good agreement with the existing experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
250. Photometric calibrations and characterization of the 4K×4K CCD imager, the first-light axial port instrument for the 3.6m DOT.
- Author
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Kumar, Amit, Pandey, S. B., Singh, Avinash, Yadav, R. K. S., Reddy, B. K., Nanjappa, N., Yadav, S., and Srinivasan, R.
- Abstract
In the present work, recent characterization results of the 4K × 4K CCD imager (a first light instrument of the 3.6m devasthal optical telescope; DOT) and photometric calibrations are discussed along with measurements of the extinction coefficients and sky brightness values at the location of the 3.6m DOT site based on the imaging data taken between 2016 and 2021. For the 4K × 4K CCD imager, all given combinations of gains (1, 2, 3, 5 and 10 e - /ADU) and readout noise values for the three readout speeds (100 kHz, 500 kHz and 1 MHz) are verified using the sky flats and bias frames taken during early 2021; measured values resemble well with the theoretical ones. Using color–color and color–magnitude transformation equations, color coefficients (α ) and zero-points (β ) are determined to constrain and examine their long-term consistencies and any possible evolution based on UBVRI observations of several Landolt standard fields observed during 2016–2021. Our present analysis exhibits consistency among estimated α values within the 1 σ and does not show any noticeable trend with time. We also found that the photometric errors and limiting magnitudes computed using the data taken using the CCD imager follow the simulated ones published earlier. The average extinction coefficients, their seasonal variations and zenith night-sky brightness values for the moon-less nights for all ten Bessell and SDSS filters are also estimated and found comparable to those reported for other good astronomical sites. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
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