34 results on '"Das NN"'
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2. Physics-Based Modeling of Active-Passive Microwave Covariations for Geophysical Retrievals
- Author
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Jagdhuber, T, primary, Entekhabi, D., additional, Das, NN., additional, Link, M., additional, Baur, M., additional, Akbar, R., additional, Montzka, C., additional, Kim, S., additional, Yueh, S., additional, and Baris, I., additional
- Published
- 2018
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3. Prognostic Relevance of Human Telomerase Reverse Transcriptase (hTERT) Expression in Patients with Gall Bladder Disease and Carcinoma
- Author
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Deblakshmi, Raj Kumari, primary, Deka, Manab, additional, Saikia, Anjan Kumar, additional, Sharma, Bir Kumar, additional, Singh, Nidhi, additional, Das, NN, additional, and Bose, Sujoy, additional
- Published
- 2015
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4. Spatiotemporal evolution of global long-term patterns of soil moisture.
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Lal P, Shekhar A, Gharun M, and Das NN
- Abstract
Surface soil moisture (SM) is essential for existence of biotic lifeform and geophysical processes. However, with increasing global warming due to climatic changes, its spatiotemporal evolution is uncertain and largely unknown. In this study we detected long-term (40 years; 1981-2020) SM patterns of global vegetated areas through spatial timeseries clustering using the state-of-the-art ERA5-Land dataset. In addition, we also analyzed long-term patterns of precipitation (P), evapotranspiration (bare soil evaporation (BSe) and vegetation transpiration (VT)), and normalized difference vegetation index (NDVI). Our results indicate that surface SM (0-7 cm depth) of about 48 % and 9 % of the global vegetated area is showing drying and wetting pattern over the past 40 years, respectively. The detected soil drying, and wetting patterns were largely consistent across different soil depth, with 90 % and 80 % pattern similarity of surface soil layer with 2
nd soil layer (7-28 cm) and 3rd soil layer (28-100 cm), respectively. About 80 % of areas with drying soil pattern also showed increasing evapotranspiration and/or decreasing precipitation. Specifically, decreasing P, increasing BSe and VT pattern were detected for 11 % of the soil drying pattern area. Similarly, increasing BSe and VT pattern, only decreasing P and only increasing VT pattern were detected for 17 %, 25 % and 12 % of soil drying areas, respectively. Both decreasing precipitation and increasing evapotranspiration patterns showed about 40 % similarity with decreasing soil moisture patterns. Across different landcover types, broadleaved forests, and cropland areas showed largest drying pattern. Under the future global warming scenario, the global soil water is expected to decrease as evapotranspiration would increase with inconsistent trend of global precipitation change. Our findings are of utmost importance for global soil water resource conservation and management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2023
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5. Monoclonal antibodies in breast cancer: A critical appraisal.
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Behl A, Wani ZA, Das NN, Parmar VS, Len C, Malhotra S, and Chhillar AK
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- Humans, Female, Antibodies, Monoclonal therapeutic use, Cell Proliferation, Breast Neoplasms drug therapy, Triple Negative Breast Neoplasms drug therapy
- Abstract
In breast cancer, mAbs can play multifunctional roles like targeting cancer cells, sometimes directly attacking them, helping in locating and delivering therapeutic drugs to targets, inhibiting cell growth and blocking immune system inhibitors, etc. Monoclonal antibodies are also one of the important successful treatment strategies especially against HER2 but they have not been explored much for other types of breast cancers especially in triple negative breast cancers. Monoclonal antibodies impact the feasibility of antigen specificity, bispecific and trispecific mAbs have opened new doors for more targeted specific efficacy. Monoclonal antibodies can be used diversly and with efficacy as compared to other methods of treatment thus maining it a suitable candidate for breast cancer treatment. However, mAbs treatment also causes various side effects such as fever, trembling, fatigue, headache and muscle pain, nausea/vomiting, difficulty in breathing, rashes and bleeding. Understanding the pros and cons of this strategy, we have explored in this review, the current and future potential capabilities of monoclonal antibodies with respect to diagnosis and treatment of breast cancer. DATA AVAILABILITY: Not applicable., Competing Interests: Conflicts of interest Authors declare that they have no competing or conflicts of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)
- Published
- 2023
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6. Computational Design for Identification of Human Anti-MUC1 Heteroclitic Peptides in the Treatment of HER2-Positive Breast Cancer through Neural Network Training and Monomeric based Design.
- Author
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Behl A, Das NN, Sharma KK, Sharma N, Gulia P, and Chhillar AK
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- Humans, Female, Peptides, Neural Networks, Computer, Breast Neoplasms drug therapy, Breast Neoplasms metabolism
- Abstract
Aims: Generation of the human anti-MUC1 peptide through neural network training and monomeric design method. Analyzing 9-mer peptide potential computationally for treatment of HER2-positive breast cancer., Background: With the advancements of cancer genome atlas project (TCGA), cancer dependancy project (DepMap) and human protein atlas (HPA), large-scale datasets are generated for oncology studies. However, after development of redefined breast cancer drug targets, there are key issues in successful breast cancer treatments that needed to be pursued which paved the pathway for new approaches or strategies. In that respect, our research data aimed to represent a new aspect of breast cancer drug development studies., Objective: Extract human MUC1 sequences from various databases. Perform neural networking method for novel peptides sequences. Analyze the potentiality of generated heteroclitic peptide sequences for suitable vaccine candidate for breast cancer treatment., Methods: Input scaffolds of protein database (PDB) files for human MUC1 were retrieved and loaded into Evo design server with monomeric based design option. Further, neural network training approaches were followed and other computational tools were used for alignment-independent prediction of protective antigens and subunit vaccines potency of designed heteroclitic peptides., Results: Study findings revealed two human anti-MUC1 heteroclitic peptides of 9mers (WAVWTYVSV, FMSFYIMNL), which showed the lowest energy cluster and sequence identity, normalized relative error rate of secondary structure, solvent accessibility, backbone torsion angles for neural networking and RMSD values in evolutionary profiling, and online MHCPred IC50 interaction values. VaxiGen v2.0 server revealed subunit vaccine potency values of in-silico designed two heteroclitic peptides were 0.1551 (WAVWTYVSV) and 0.3508 (FMSFYIMNL) with a threshold value of 0.5 followed by AllerTOP v2.0 for their allergenicity nature in immunogenic reactions., Conclusion: Computationally designed heteroclitic peptide WAVWTYVSV indicated promising values which can be utilised as drug delivery or tumour marker candidate in the treatment of human breast cancer by eliciting lyse of tumor cells., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)
- Published
- 2023
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7. A data-driven approach using the remotely sensed soil moisture product to identify water-demand in agricultural regions.
- Author
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Singh G and Das NN
- Subjects
- Agriculture, Dehydration, Environmental Monitoring methods, Humans, Remote Sensing Technology, Soil
- Abstract
Effective agricultural water management requires accurate and timely identification of crop water stress at the farm-scale for irrigation advisories or to allocate the optimal amount of water for irrigation. Various drought indices are being utilized to map the water-stressed locations/farms in agricultural regions. Most of these existing drought indices provide some degree of characterization of water stress but do not adequately provide spatially resolved high-resolution (farm-scale) information for decision-making about irrigation advisories or water allocation. These existing drought indices need modeling and climatology information, hence making them data-intensive and complex to compute. Therefore, a reliable, simple, and computationally easy method without modeling to characterize the water stress at high-resolution is essential for the operational mapping of water-stressed farms in agricultural regions. The proposed new approach facilitates improved and quick decision-making without compromising much of the skills imparted by the established drought indices. This study aims to formulate a water-demand index (WDI) based on a parameter-independent data-driven approach using readily available remote sensing observations and weather data. We hypothesize that the WDI for an agricultural domain can be characterized by soil moisture, vegetative growth (NDVI), and heat unit (growing degree day, GDD). To this end, we used remote sensing-based soil moisture and NDVI and modeled ambient temperature datasets to generate weekly WDI maps at 1 km. The proposed methodology is verified over a few intensively irrigated agricultural-dominated areas with different climatic conditions. Our results suggest that the proposed approach characterizes water-stressed fields through WDI maps with good spatial representativeness. Overall, this study provides a framework to generate weekly WDI maps quickly with readily available measurements. These water-demand maps will help water resource managers to reduce dependence on established drought indices and prioritize the specific regions/fields with high water demand for optimum water allocations to improve crop health and ultimately maximize water-use efficiency., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Narendra N. Das reports financial support was provided by NASA through Michigan State University. Narendra N. Das reports a relationship with Michigan State University that includes: employment., (Copyright © 2022 Elsevier B.V. All rights reserved.)
- Published
- 2022
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8. Surgical outcome of empyema thoracis patients with special correlation to pre-operative contrast-enhanced computerized tomography (CECT) thorax morphometry.
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Das NN, Lakhotia S, and Verma A
- Abstract
Purpose: Empyema thoracis is a very common disease. The surgical outcome of empyema patients depends upon various factors. To the best of our knowledge, there is no study in literature describing the surgical outcome of patients in relation to the contrast-enhanced computerized tomography (CECT) thorax morphometric findings. In this study, we examined the surgical outcome of empyema thoracis patients in relation to both clinical and radiological findings., Materials and Methods: It is a prospective hospital-based study conducted between October 2016 and August 2018. A total of 30 patients, who underwent decortication during the study period, were included. They were divided into three performance groups (excellent performance, average performance and poor performance groups) according to the outcome. The surgical outcome was correlated with the pre-operative clinical, radiological, intra-operative and post-operative parameters., Results: Intra-operative ability to complete decortication, intra-operative expansion of the lungs and presence of broncho-pleural fistula were significantly different between the three performance groups. Duration of the disease, pre-operative duration of antitubercular therapy (ATT) intake and duration of pre-operative intercostal drain (ICD) were statistically insignificant between groups. In computed tomography (CT) morphometry, residual lung volume of the involved lung and volume of empyema were found to be significantly different between the performance groups. The residual volume of the involved lung (expressed in terms of the percentage of lung volume of the normal opposite lung) can predict the complete expansion of the lung with sensitivity of 71% and specificity of 70%., Conclusion: The pre-operative residual lung volume of the involved lung, empyema volume, completeness of decortication, intra-operative expansion of the lung and presence or absence of broncho-pleural fistula can determine the surgical outcome in empyema thoracis patients., Competing Interests: Conflict of interestThe authors declare that they have no conflicts of interest., (© Indian Association of Cardiovascular-Thoracic Surgeons 2020.)
- Published
- 2021
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9. Metaheuristic-based Deep COVID-19 Screening Model from Chest X-Ray Images.
- Author
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Kaur M, Kumar V, Yadav V, Singh D, Kumar N, and Das NN
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- Algorithms, Humans, Neural Networks, Computer, Sensitivity and Specificity, COVID-19 diagnostic imaging, Deep Learning, Image Interpretation, Computer-Assisted methods, Radiography, Thoracic
- Abstract
COVID-19 has affected the whole world drastically. A huge number of people have lost their lives due to this pandemic. Early detection of COVID-19 infection is helpful for treatment and quarantine. Therefore, many researchers have designed a deep learning model for the early diagnosis of COVID-19-infected patients. However, deep learning models suffer from overfitting and hyperparameter-tuning issues. To overcome these issues, in this paper, a metaheuristic-based deep COVID-19 screening model is proposed for X-ray images. The modified AlexNet architecture is used for feature extraction and classification of the input images. Strength Pareto evolutionary algorithm-II (SPEA-II) is used to tune the hyperparameters of modified AlexNet. The proposed model is tested on a four-class (i.e., COVID-19, tuberculosis, pneumonia, or healthy) dataset. Finally, the comparisons are drawn among the existing and the proposed models., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2021 Manjit Kaur et al.)
- Published
- 2021
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10. Pediatric intrahepatic bile duct adenoma - rare liver tumor: A case report.
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Roy AK and Das NN
- Abstract
Background: Intrahepatic bile duct adenoma (BDA) is one of the rarest of the rare benign tumors of the liver in the pediatric age group. It arises from the epithelial lining of intrahepatic bile ducts. The overall incidence of BDA is 1.3% of all primary benign liver tumors. Few case reports of this rare tumor occurring in adult population are present in the literature and to date, only one pediatric case has been reported worldwide., Case Summary: An 18-month-old male child presented with chief complaints of mass per abdomen for 8 mo. Computerized tomography abdomen revealed a well-defined exophytic solid tumor arising from the posteroinferior margin of the right lobe of the liver with heterogenous enhancement and cystic changes, suggesting a suspicion of hepatoblastoma. Non-anatomical liver resection was done and a tumor of 10 cm × 9.5 cm was excised. Histopathology of the specimen was conclusive with the diagnosis of intrahepatic bile duct adenoma, which was further supported by immunohistochemistry panel testing. The post-operative period was uneventful. On follow-up, the child was doing well and had no post-operative complication., Conclusion: Intrahepatic bile duct adenoma in children is very rare and to date only one case has been reported. This is the second pediatric case of intrahepatic bile duct adenoma in the world. Additionally this is the first ever case of such a large tumor presenting in a child., Competing Interests: Conflict-of-interest statement: To the best of our knowledge, no conflict of interest exists., (©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.)
- Published
- 2019
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11. Evaluation of SMAP downscaled brightness temperature using SMAPEx-4/5 airborne observations.
- Author
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Ye N, Walker JP, Bindlish R, Chaubell J, Das NN, Gevaert AI, Jackson TJ, and Rüdiger C
- Abstract
The Soil Moisture Active and Passive (SMAP) mission, launched by the National Aeronautics and Space Administration (NASA) on 31
st January 2015, was designed to provide global soil moisture every 2 to 3 days at 9 km resolution by downscaling SMAP passive microwave observations obtained at 36 km resolution using active microwave observations at 3 km resolution, and then retrieving soil moisture from the resulting 9 km brightness temperature product. This study evaluated the SMAP Active/Passive (AP) downscaling algorithm together with other resolution enhancement techniques. Airborne passive microwave observations acquired at 1 km resolution over the Murrumbidgee River catchment in south-eastern Australia during the fourth and fifth Soil Moisture Active Passive Experiments (SMAPEx-4/5) were used as reference data. The SMAPEx-4/5 data were collected in May and September 2015, respectively, and aggregated to 9 km for direct comparison with a number of available resolution-enhanced brightness temperature estimates. The results show that the SMAP AP downscaled brightness temperature had a correlation coefficient (R) of 0.84 and Root-Mean-Squared Error (RMSE) of ~10 K, while SMAP Enhanced, Nearest Neighbour, Weighted Average, and the Smoothing Filter-based Modulation (SFIM) brightness temperature estimates had somewhat better performance (RMSEs of ~7 K and an R exceeding 0.9). Although the SFIM had the lowest unbiased RMSE of ~6 K, the effect of cloud cover on Ka-band observations limits data availability.- Published
- 2019
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12. Joint Sentinel-1 and SMAP data assimilation to improve soil moisture estimates.
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Lievens H, Reichle RH, Liu Q, De Lannoy GJM, Dunbar RS, Kim SB, Das NN, Cosh M, Walker JP, and Wagner W
- Abstract
SMAP (Soil Moisture Active and Passive) radiometer observations at ~40 km resolution are routinely assimilated into the NASA Catchment Land Surface Model to generate the 9-km SMAP Level-4 Soil Moisture product. This study demonstrates that adding high-resolution radar observations from Sentinel-1 to the SMAP assimilation can increase the spatio-temporal accuracy of soil moisture estimates. Radar observations were assimilated either separately from or simultaneously with radiometer observations. Assimilation impact was assessed by comparing 3-hourly, 9-km surface and root-zone soil moisture simulations with in situ measurements from 9-km SMAP core validation sites and sparse networks, from May 2015 to December 2016. The Sentinel-1 assimilation consistently improved surface soil moisture, whereas root-zone impacts were mostly neutral. Relatively larger improvements were obtained from SMAP assimilation. The joint assimilation of SMAP and Sentinel-1 observations performed best, demonstrating the complementary value of radar and radiometer observations.
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- 2017
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13. [The network social support experience of people involved in home care].
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Gomes IM, Lacerda MR, and Mercês NN
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- Humans, Models, Theoretical, Caregivers, Home Care Services, Social Support
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Objective: To build a theoretical model to configure the network social support experience of people involved in home care., Method: A quantitative approach research, utilizing the Grounded Theory method. The simultaneous data collection and analysis allowed the interpretation of the phenomenon meaning The network social support of people involved in home care., Results: The population passive posture in building their well-being was highlighted. The need of a shared responsibility between the involved parts, population and State is recognized., Conclusion: It is suggested for nurses to be stimulated to amplify home care to attend the demands of caregivers; and to elaborate new studies with different populations, to validate or complement the proposed theoretical model.
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- 2014
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14. Characterizing toxic Cr(VI) contamination in chromite mine overburden dump and its bacterial remediation.
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Dhal B, Das NN, Thatoi HN, and Pandey BD
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- Biodegradation, Environmental, Electron Probe Microanalysis, Hydrogen-Ion Concentration, India, Microscopy, Electron, Scanning, Spectroscopy, Fourier Transform Infrared, Temperature, Time Factors, X-Ray Diffraction, Bacillus metabolism, Chromium chemistry, Mining, Soil Pollutants chemistry
- Abstract
Cr(VI) generated due to natural oxidation of chromite mineral present in chromite mine overburden (COB) dumps of Sukinda, India, has been characterized by different physico-chemical methods. The Cr(VI) was found to be associated with goethite matrix at a contamination level of 500 mg Cr(VI)kg(-1) of COB. Bacillus sp. isolated from the overburden sample exhibiting high tolerance to the hexavalent chromium, was used for the remediation of Cr(VI) in the overburden. The process was optimized while varying the parameters such as pH (2-9), pulp density (10-60%) and temperature (25-40 °C). Optimal reduction of more than 98% of Cr(VI) in the COB sample was achieved in 16 h at pH∼7.0 and 60% pulp density with the Bacillus sp. (4.05 × 10(7)cells mL(-1)) in absence of media. The exponential rate equation yielded rate constant value of 2.14 × 10(-1)h(-1) at 60% pulp density. The mode of bio-reduction of Cr(VI) in the overburden sample was established by FT-IR, XRD, EPMA and SEM-EDS studies., (Copyright © 2013 Elsevier B.V. All rights reserved.)
- Published
- 2013
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15. Chemical and microbial remediation of hexavalent chromium from contaminated soil and mining/metallurgical solid waste: a review.
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Dhal B, Thatoi HN, Das NN, and Pandey BD
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- Adsorption, Chromium analysis, Chromium chemistry, Hydrogen-Ion Concentration, Industrial Waste, Models, Chemical, Oxygen chemistry, Refuse Disposal, Soil, Soil Microbiology, Soil Pollutants metabolism, Solid Waste, Chromium toxicity, Environmental Restoration and Remediation, Soil Pollutants analysis
- Abstract
Chromium is a highly toxic non-essential metal for microorganisms and plants, and its occurrence is rare in nature. Lower to higher chromium containing effluents and solid wastes released by activities such as mining, metal plating, wood preservation, ink manufacture, dyes, pigments, glass and ceramics, tanning and textile industries, and corrosion inhibitors in cooling water, induce pollution and may cause major health hazards. Besides, natural processes (weathering and biochemical) also contribute to the mobility of chromium which enters in to the soil affecting the plant growth and metabolic functions of the living species. Generally, chemical processes are used for Cr- remediation. However, with the inference derived from the diverse Cr-resistance mechanism displayed by microorganisms and the plants including biosorption, diminished accumulation, precipitation, reduction of Cr(VI) to Cr(III), and chromate efflux, bioremediation is emerging as a potential tool to address the problem of Cr(VI) pollution. This review focuses on the chemistry of chromium, its use, and toxicity and mobility in soil, while assessing its concentration in effluents/wastes which becomes the source of pollution. In order to conserve the environment and resources, the chemical/biological remediation processes for Cr(VI) and their efficiency have been summarised in some detail. The interaction of chromium with various microbial/bacterial strains isolated and their reduction capacity towards Cr(VI) are also discussed., (Copyright © 2013 Elsevier B.V. All rights reserved.)
- Published
- 2013
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16. Selenite adsorption using leached residues generated by reduction roasting-ammonia leaching of manganese nodules.
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Randhawa NS, Das NN, and Jana RK
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- Adsorption, Hot Temperature, Hydrogen-Ion Concentration, Oxidation-Reduction, Surface Properties, Ammonia chemistry, Manganese Compounds chemistry, Sodium Selenite isolation & purification, Water Pollutants, Chemical isolation & purification, Water Purification methods
- Abstract
This study was carried out to investigate the adsorption characteristics of leached manganese nodule residue (MNR), generated from the reduction roasting-ammonia leaching process, towards aqueous selenite. Physicochemical characterization revealed that the leached residue was a complex mixture of oxides of mainly manganese and iron along with MnCO(3). Adsorption studies of the water washed leached residue (wMNR) at varying the pH, selenite ion concentration, wMNR dosage, heat treatment condition indicated that selenite uptake increased with increasing pH and heat-treatment temperature of wMNR. The maximum value of selenite uptake was obtained at pH ~5.0 with wMNR heat-treated at 400°C and thereafter decreased on increasing the pH and heat-treatment temperature further. The adsorption data were best fitted by the Freundlich isotherm model. The derived monolayer selenite adsorption capacities increased from, X(m)=9.50 mg Se/g (for untreated wMNR) to 15.08 mg Se/g (for wMNR heat-treated at 400°C). The results of the studies may be useful for possible utilization of MNR as an adsorbent for the removal of selenite ions from contaminated water bodies., (Copyright © 2012 Elsevier B.V. All rights reserved.)
- Published
- 2012
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17. Optimization and characterization of chromium(VI) reduction in saline condition by moderately halophilic Vigribacillus sp. isolated from mangrove soil of Bhitarkanika, India.
- Author
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Mishra RR, Dhal B, Dutta SK, Dangar TK, Das NN, and Thatoi HN
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- Biodegradation, Environmental drug effects, Chromium toxicity, India, Oxidation-Reduction, RNA, Bacterial genetics, RNA, Ribosomal, 16S genetics, Sodium Chloride pharmacology, Soil Pollutants toxicity, Virgibacillus drug effects, Virgibacillus genetics, Virgibacillus isolation & purification, Chromium metabolism, Soil Pollutants metabolism, Virgibacillus metabolism
- Abstract
A Gram-positive moderately halophilic Cr(VI) tolerant bacterial strain H4, isolated from saline mangrove soil, was identified as Vigribacillus sp. by biochemical characterization and 16S rRNA analysis. In LB medium, the strain could tolerate up to 1000 mg L(-1) Cr(VI) concentration and reduced 90.2 and 99.2% of 100 mg L(-1) Cr(VI) under optimized set of condition within 70 h in absence and presence of 6 wt.% NaCl, respectively. The fitting of time course reduction data to an exponential rate equation yielded the Cr(VI) reduction rate constants in the range (0.69-5.56)×10(-2)h(-1). Analyses of total chromium and bacterial cell associated with reduced product by AAS, SEM/EDS, TEM/SAED, FT-IR and UV-vis-DRS indicated the formation of about 35% of insoluble Cr(III) either as Cr(OH)(3) precipitate in nanometric size or immobilized on the bacterial cell surface while the remaining 65% of reduced chromium was present as soluble Cr(III) in the growth medium. Powder XRD analysis revealed the amorphous nature of the precipitated Cr(OH)(3). The high Cr(VI) reducing ability of the strain under saline condition suggests the Vigribacillus sp. as a new and efficient strain capable of remediating highly saline Cr(VI) polluted industrial effluents., (Copyright © 2012 Elsevier B.V. All rights reserved.)
- Published
- 2012
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18. Oxidative decolorization of methylene blue by leached sea-nodule residues generated by the reduction-roasting ammoniacal leaching process.
- Author
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Satapathy PK, Randhawa NS, and Das NN
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- Oxidation-Reduction, Ammonia chemistry, Geologic Sediments chemistry, Metals chemistry, Methylene Blue chemistry, Methylene Blue isolation & purification, Water Pollutants, Chemical chemistry, Water Pollutants, Chemical isolation & purification, Water Purification methods
- Abstract
The leached residue, generated after selective extraction of Cu, Ni and Co by reductive-roasting ammoniacal leaching of sea nodules, was characterized by various physicochemical methods. The finely divided residue, containing mainly manganese carbonate/silicates and manganese (III, IV) (hydr)oxides along with iron oxides, showed a lower surface area (66.3 m2 g(-1)) than that of the parent sea nodule (130 m2 g(-1)). The catalytic efficiency of water-washed sea nodule residue (WSNR) was evaluated taking oxidative decolorization of methylene blue (MB) as the test reaction. The extent of decolorization was decreased with increase in pH but increased in the presence of H2O2 or NaCl. Decolorization of MB occurred in two consecutive steps; the rate constant of the first step was -10 times higher than that of the second step. The formation of a surface precursor complex between WSNR and MB at a rate-limiting step, followed by electron transfer from MB to the active metal centre of WSNR and release of product(s), was proposed as the decolorization process.
- Published
- 2012
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19. Extraction of cadmium from dilute solution using supported liquid membrane.
- Author
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Parhi PK, Das NN, and Sarangi K
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- Diffusion, Hydrogen-Ion Concentration, Organophosphates, Permeability, Phosphinic Acids, Solutions, Cadmium isolation & purification, Membranes, Artificial
- Abstract
The extraction efficiencies of three phosphoric acid derivatives (D2EHPA, PC-88A and Cyanex 272) for Cd in supported liquid membrane (SLM) have been reported. The equilibrium study indicated the release of two moles of H(+) ions from the extractant for extraction of one mole of cadmium ion and association of two moles of the extractants in the extracted species in each case. The diffusion constant of Cd-D2EHPA, Cd-PC-88A and Cd-Cyanex 272 complex through the membrane phase was found to be 2.53 x 10(-9), 5.435 x 10(-9) and 11.22 x 10(-9)m(2)/s, respectively. The effects of various parameters such as flow rate, pH of feed solution, concentration of extractants in membrane phase, concentration of H(2)SO(4) in strip solution and concentration of Cd in feed solution on cadmium flux (J(Cd)) have been investigated. At pH 7.5, the percentage of cadmium extraction was found to be maximum with 600 mol/m(3) D2EHPA and PC-88A and 800 mol/m(3) Cyanex 272. The extraction of cadmium using the phosphoric acid derivative follows the order D2EHPA>PC-88A>Cyanex 272.
- Published
- 2009
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20. Adsorption of Cr(VI) and Se(IV) from their aqueous solutions onto Zr4+-substituted ZnAl/MgAl-layered double hydroxides: effect of Zr4+ substitution in the layer.
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Das NN, Konar J, Mohanta MK, and Srivastava SC
- Abstract
Hydrotalcite-like compounds (layered double hydroxides, LDHs) containing varying amounts of Al(3+), Zr(4+), and Zn(2+) or Mg(2+) in the metal hydroxide layer have been synthesized and characterized by various physicochemical methods. The adsorption behavior of uncalcined (as-synthesized) and calcined LDHs have been investigated for Cr(2)O(7)(2-) and SeO(3)(2-). The mixed oxides, obtained on calcination at 450 degrees C, exhibit high adsorption capacities for Cr(2)O(7)(2-) (1.6-2.7 meq/g) and SeO(3)(2-) (1.1-1.5 meq/g), where adsorption occurs through rehydration. Substitution of Zr(4+) in the LDHs, for either M(2+) or Al(3+) ions, increases the adsorption capacity up to 20%, thus providing an alternative way to enhance the adsorption capacity of this type of material. The high adsorption capacity of these materials could be successfully used for removal of undesirable anions from water and also for synthesis of intercalated materials with tailored acidobasicity.
- Published
- 2004
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21. Studies on Indian Ocean Manganese Nodules
- Author
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Parida KM, Samal A, and Das NN
- Abstract
The oxidation of thiols to corresponding disulfides by Indian Ocean ferromanganese nodules has been studied under varying experimental conditions. More than 90% conversion of thiols (2.5 x 10(-3) mol) was achieved at 35°C using 0.1 g nodules. The oxides of Mn, Fe, Ca, Mg, and Al and surface oxygen in the nodules are most likely responsible for the oxidation of thiols. Under identical conditions the oxidative conversion of thiols decreases in the order 1-dodecanethiol < 1-hexanethiol < 1,4-butanedithiol < alpha-toluenethiol. Copyright 1998 Academic Press. Copyright 1998Academic Press
- Published
- 1998
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22. Studies on Indian Ocean Manganese Nodules
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Parida KM, Gorai B, and Das NN
- Abstract
Adsorption of aqueous selenite (SeO32-) on Indian Ocean manganese nodules was studied as a function of time, temperature, pH, and concentrations of adsorbate and adsorbent in acetic acid-sodium acetate buffer medium. Analysis of adsorption data supports a heterogeneous nature for the surface of manganese nodules. The adsorption capacity of various manganese nodules for selenite was correlated with their chemical composition and surface properties.
- Published
- 1997
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23. Studies on Ferric Oxide Hydroxides
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Parida KM, Gorai B, Das NN, and Rao SB
- Abstract
Adsorption of selenite (SeO2-3) on different polymorphic forms of iron oxyhydroxides and amorphous ferrihydrite was studied as a function of time, temperature, pH, and concentration of adsorbate(s) and adsorbent(s). Analysis of adsorption data indicates that the surfaces of all the forms of oxyhydroxides and ferrihydrite are heterogeneous in nature and that adsorption fits into a heterogeneous site binding model. The adsorption capacity of oxyhydroxides for SeO2-3 follows the order beta-FeOOH < alpha-FeOOH < gamma-FeOOH < delta-FeOOH < ferrihydrite.
- Published
- 1997
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24. Studies on Indian Ocean Manganese Nodules
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Parida KM, Sahoo AK, and Das NN
- Abstract
A series of rare earth oxide mixed manganese nodules (perovskite type mixed oxides) have been prepared by coprecipitation method followed by calcination at 900°C and characterized by different techniques. The effect of rare earth ions on the surface, textural and catalytic activity for the oxidation of CO, and decomposition of H2O2 have been discussed. The activity for CO oxidation followed an order: Pr >/= La > Nd > Yb > Dy > Tb > Sm > Tm > Gd > Eu > Ce.
- Published
- 1996
- Full Text
- View/download PDF
25. Structure of the D-galactan isolated from garlic (Allium sativum) bulbs.
- Author
-
Das NN and Das A
- Subjects
- Galactose analysis, Garlic analysis, Monosaccharides analysis, Plants, Medicinal, Plants analysis, Polysaccharides isolation & purification
- Abstract
Hot-water extraction of defatted garlic-bulbs yielded a mixture of polysaccharides containing a D-galactan, a D-galacturonan, an L-arabinan, a D-glucan, and a D-fructan. A trace of L-rhamnose was also detected in the polysaccharide hydrolyzate. The pectic acid was partially removed by precipitation with aqueous calcium chloride; from the remaining polysaccharide mixture, a pure D-galactan containing 97.3% of D-galactose was isolated by fractional precipitation and repeated chromatography through a column of DEAE-cellulose. Methanolysis and hydrolysis of the permethylated D-galactan yielded 2,3,4,6-tetra-, 2,3,6-tri-, and 2,3,di-O-methyl-D-galactose in the molar proportions of 1:2:1. On periodate oxidation, the D-galactan reduced 1.18 molar equivalents of the oxidant per D-galactosyl residue, and liberated one molar equivalent of formic acid per 4.13 D-galactosyl residues. Smith degradation of the D-galactan was also conducted. From these results, a structure has been assigned to the repeating unit of the D-galactan.
- Published
- 1977
- Full Text
- View/download PDF
26. Geriforte in anxiety neurosis.
- Author
-
Boral GC, Bandopadyaya G, Boral A, Das NN, and Nandi PS
- Published
- 1989
27. Mental morbidity and urban life-an epidemiological study.
- Author
-
Nandi DN, Das NN, Chaudhuri A, Banerjee G, Datta P, Ghosh A, and Boral GC
- Abstract
A survey of the mental morbidity of an urban group and two rural groups was made with the same method, same operational definition of a case and by the same team. The aim was to find out the nature and extent of the difference in their rates of morbidity and to identify the psychosocial variables associated with this difference. It was found that the rate of total morbidity was significantly higher in the urban group than in the rural groups. Psychosis was, however, commoner among the Brahmins, a rural group. The wide difference in the rates of mental morbidity between the urban and rural groups was mainly due to the difference in the rate of neurosis (165.3/1000, 51.6/1000 and 1.5/1000 respectively). The rate of neurosis in its turn was considered to be positively correlated with certain psychosocial characteristics irrespective of urban or rural residence of the group concerned.
- Published
- 1980
28. Diathermy in Pneumonia.
- Author
-
Das NN
- Published
- 1931
29. The effect of chlorpromazine on the electrical activity of the cerveau isole.
- Author
-
DAS NN, DASGUPTA SR, and WERNER G
- Subjects
- Humans, Brain physiology, Chlorpromazine pharmacology, Electroencephalography drug effects, Nervous System Physiological Phenomena
- Published
- 1955
- Full Text
- View/download PDF
30. Laboratory Procedures, Apparatus and Improvizations.
- Author
-
Pasricha CL, Das NN, Malik KS, deMonte AJH, and Banerjee K
- Published
- 1941
31. Haemodynamic effects of rauwolscine.
- Author
-
DAS NN, DASGUPTA SR, MUKHERJEE KL, and WERNER G
- Subjects
- Antihypertensive Agents, Blood drug effects, Hemodynamics, Secologanin Tryptamine Alkaloids pharmacology, Yohimbine
- Published
- 1955
32. Changes of behaviour and electroencephalogram in rhesus monkeys caused by chlorpromazine.
- Author
-
DAS NN, DASGUPTA SR, and WERNER G
- Subjects
- Animals, Behavior drug effects, Chlorpromazine pharmacology, Electroencephalography drug effects, Macaca mulatta
- Published
- 1954
33. Immunity after intradermal inoculation of cholera vaccine.
- Author
-
PANJA G and DAS NN
- Subjects
- Humans, Cholera, Cholera Vaccines, Immunity, Vaccination
- Published
- 1947
34. Treatment of Smallpox with an Antigen-Antibody Mixture.
- Author
-
Panja G and Das NN
- Published
- 1942
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