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Electro-magnetohydrodynamic Flow of Biofluid Induced by Peristaltic Wave： A Non-newtonian Model

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Journal of Bionic Engineering 2016年第3期13卷 436-448页

作者： gopal chandra shit Nayan Kumar Ranjit Aniruddha Sinha Department of Mathematics Jadavpur University Kolkata - 700032 India Yogoda Satsanga Palpara Mahavidyalaya Purba Medinipur - 721458 India

This article aims to develop a mathematical model for peristaltic transport of magnetohydrodynamic flow of biofluids through a micro-channel with rhythmically contracting and expanding walls under the influence of an applied electric field. The couple stress fluid model is considered to represent the non-Newtonian characteristics ofbiofluids. The velocity slip condition at the channel walls is taken into account because of the hyclrophilic/hydrophobic interaction with negatively charged walls. The essential features of the electromagnetohydrodynamic flow of biofluid through micro-channels are clearly highlighted in the variations of the non-dimensional parameters of the physical quantities of interest such as the velocity, wall shear stress, pressure gradient, pressure rise per wave length, frictional force at the channel walls and the distribution of stream function. It reveals that the flow ofhiofluid is appreciably influenced by the sufficient strength of externally applied magnetic field and electro-osmotic parameter. The velocity slip condition reduces the frictional force at the channel wall. Moreover, the formation of the trapping bolus strongly depends on electro-osmotic parameter and magnetic field strength.

关键词： peristaltic transport couple stress fluid magnetohydrodynamics electro-osmosis

An account of the strategies to enhance the water splitting efficiency of noble-metal-free electrocatalysts

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Journal of Energy Chemistry 2021年第8期30卷 160-190,I0005页

作者： Subhasis shit Saikat Bolar Naresh chandra Murmu Tapas Kuila Surface Engineering&Tribology Division Council of Scientific and Industrial Research-Central Mechanical Engineering Research InstituteMahatma Gandhi AvenueDurgapur 713209India Academy of Scientific and Innovative Research(AcSIR) CSIR-Human Resource Development Centre(CSIR-HRDC)CampusPostal Staff College AreaSector 19Kamla Nehru NagarGhaziabad 201002India

The electrolysis of water for hydrogen generation has shown immense promise as an energy conversion technology for the green energy *** concurrently occurring electrochemical reactions in water electrolysis(hydrogen and oxygen evolution reactions)are sluggish in nature and therefore the employment of electrocatalysts is highly ***-metal-based electrocatalysts(Pt,Ru O_(2),Ir O_(2),etc.)have shown superior activity towards these ***,their lower natural abundance and inferior stability make the cost to performance ratio of water electrolysis too ***,huge amount of research efforts are being carried out to develop electrocatalysts consisting of earth abundant elements(transition metals,carbon etc.)as the replacement of these noble-metal-based *** metal compounds,carbonaceous and hybrid materials have shown promise as efficient electrocatalysts but there is still huge gap between the activities of these materials and the noble-metal-based *** strategies like morphology modulation,elemental doping,defect engineering *** being deployed to enhance the activity of these noble-metal-free *** review summarizes these strategies and thoroughly discusses the reason behind the changes in activity of the electrocatalysts owing to these ***,the remaining research gaps and future prospects in this field are also discussed in detail.

关键词： Water splitting Electrocatalyst Morphology Doping Defect engineering Phase engineering

Electroosmotic oscillatory flow of micropolar fluid in microchannels:application to dynamics of blood flow in microfluidic devices

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Applied Mathematics and Mechanics(English Edition) 2014年第6期35卷 749-766页

作者： J.C.MISRA S.chandra G.C.shit P.K.KUNDU Department of Mathematics Institute of Technical Education and ResearchSiksha O Anusandhan University Department of Mathematics Jadavpur University

The electroosmotic flow of a micropolar fluid in a microchannel bounded by two parallel porous plates undergoing periodic vibration is studied. The equations for conservation of linear and angular momentums and Gauss＇s law of charge distribution are solved within the framework of the Debye-Hückel approximation. The fluid velocity and microrotation are assumed to depend linearly on the Reynolds number. The study shows that the amplitude of microrotation is highly sensitive to the changes in the magnitude of the suction velocity and the width of the microchannel. An increase in the micropolar parameter gives rise to a decrease in the amplitude of microrotation. Numerical estimates reveal that the microrotation of the suspended microelements in blood also plays an important role in controlling the electro-osmotically actuated flow dynamics in microbio-fluidic devices.

关键词： blood flow electrohydrodynamic effect microfluidics channel flow

Diagnosis of Helicobacter pylori : What should be the gold standard?

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World Journal of Gastroenterology 2014年第36期20卷 12847-12859页

作者： Saurabh Kumar Patel chandra Bhan Pratap Ashok Kumar Jain Anil Kumar Gulati gopal Nath Department of Microbiology Institut of Medical Sciences Banaras Hindu University Varanasi U221005 India Department of Gastroenterology Institute of Medical Sciences Banaras Hindu University Varanasi UP221005 India Department of Microbiology Institutof Medical Sciences Banaras Hindu University Varanasi U221005 India

Since the discovery of Helicobacter pylori (H. pylori) in 1983, numerous detection methods for the presence of the bacterium have been developed. Each one of them has been associated with advantages and disadvantages. Noninvasive tests such as serology, 13C urea breath test (UBT) and stool antigen tests are usually preferred by the clinicians. Serology has its own limitation especially in endemic areas while 13C UBT is technically very demanding. The stool antigen detection method, although specific, is usually associated with poor sensitivity. The 13C UBT is believed to be specific, but with present revelation of the fact that stomach is colonized by many other urease producing bacteria makes it questionable. Histology, culture, rapid urease test and polymerase chain reaction (PCR) are the tests which are carried out on antral biopsies collected by invasive means. Histology has been proposed to be very sensitive and specific but the question is how by simply looking the morphology of the bacteria in the microscope, one can claim that the curved bacterium is exclusively H. pylori. Rapid urease test (RUT), the doctor’s test, is also challenged because the presence of other urease producing bacteria in the stomach cannot be denied. Moreover, RUT has been reported with poor sensitivity specially, when density of the bacterium is low. Isolation of H. pylori is essential to investigate its growth requirements, antibiotic susceptibility testing, studying virulence factor to develop vaccine and many more explorations. It has also got several disadvantages i.e., special condition for transporting, media, incubation and few days waiting for the colonies to appear, apart from the speed essentially needed to process the specimens. Till date, majority of the microbiological laboratories in the world are not equipped and trained to isolate such fastidious bacterium. The option left is PCR methods to detect H. pylori’s DNA in gastr

关键词： Helicobacter pylori review Invasive tests Non-invasive tests Gold standard Polymerase chain reaction detection Nested polymerase chain reaction

COVID-19 strict lockdown impact on urban air quality and atmospheric temperature in four megacities of India

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Geoscience Frontiers 2022年第6期13卷 279-290页

作者： Subodh chandra Pal Indrajit Chowdhuri Asish Saha Manoranjan Ghosh Paramita Roy Biswajit Das Rabin Chakrabortty Manisa shit Department of Geography The University of BurdwanBardhaman713104West BengalIndia Center for Rural Development and Innovative Sustainable Technology Indian Institute of Technology KharagpurWest Bengal721302India India Smart Cities Fellow National Institute of Urban AffairsNew Delhi110003India Department of Geography Raiganj UniversityRaiganjUttar Dinajpur733134West BengalIndia

COVID-19 pandemic has forced to lockdown entire India starting from 24th March 2020 to 14th April 2020(first phase), extended up to 3rd May 2020(second phase), and further extended up to 17th May 2020(third phase) with limited relaxation in non-hotspot areas. This strict lockdown has severely curtailed human activity across India. Here, aerosol concentrations of particular matters(PM) i.e., PM,PM, carbon monoxide(CO), nitrogen dioxide(NO), sulphur dioxide(SO), ammonia(NH) and ozone(O), and associated temperature fluctuation in four megacities(Delhi, Mumbai, Kolkata, and Chennai)from different regions of India were investigated. In this pandemic period, air temperature of Delhi,Kolkata, Mumbai and Chennai has decreased about 3 ℃, 2.5 ℃, 2 ℃ and 2 ℃ respectively. Compared to previous years and pre-lockdown period, air pollutants level and aerosol concentration(-41.91%,-37.13%,-54.94% and-46.79% respectively for Delhi, Mumbai, Kolkata and Chennai) in these four megacities has improved drastically during this lockdown period. Emission of PMhas experienced the highest decrease in these megacities, which directly shows the positive impact of restricted vehicular movement. Restricted emissions produce encouraging results in terms of urban air quality and temperature, which may encourage policymakers to consider it in terms of environmental sustainability.

关键词： COVID-19 Aerosol Air pollutant Climate Megacity

Pseudomonas fluorescens-like bacteria from the stomach:A microbiological and molecular study

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World Journal of Gastroenterology 2013年第7期19卷 1056-1067页

作者： Saurabh Kumar Patel chandra Bhan Pratap Ajay Kumar Verma Ashok Kumar Jain Vinod Kumar Dixit gopal Nath Department of Microbiology Institute of Medical SciencesBanaras Hindu UniversityVaranasi UP 221005India Department of Gastroenterology Institute of Medical SciencesBanaras Hindu UniversityVaranasi UP 221005India

AIM:To characterize oxidase-and urease-producing bacterial isolates,grown aerobically,that originated from antral biopsies of patients suffering from acid peptic ***:A total of 258 antral biopsy specimens were subjected to isolation of bacteria followed by tests for oxidase and urease production,acid tolerance and aerobic *** selected isolates were further characterized by molecular techniques *** for 16S rRNA using universal eubacterial and HSP60 gene specific *** amplicons were subjected to restriction analysis and partial sequencing.A phylogenetic tree was generated using unweighted pair group method with arithmetic mean(UPGMA) from evolutionary distance computed with bootstrap test of *** of acidity tolerance of bacteria isolated from antrum was performed using hydrochloric acid from 10-7 mol/L to 10-1 mol/***:Of the 258 antral biopsy specimens collected from patients,179(69.4%) were positive for urease production by rapid urease test and 31%(80/258) yielded typical Helicobacter pylori(***) after 5-7 d of incubation under a microaerophilic environment.A total of 240(93%) antral biopsies yielded homogeneous semi-translucent and small colonies after overnight *** partial 16S rRNA sequences revealed that the isolates had 99% similarity with Pseudomonas species.A phylogenetic tree on the basis of 16S rRNA sequences denoted that JQ927226 and JQ927227 were likely to be related to Pseudomonas fluorescens(***).On the basis ofHSP60 sequences applied to the UPGMA phylogenetic tree,it was observed that isolated strains in an aerobic environment were likely to be ***,and HSP60 sequences had more discriminatory potential rather than 16S rRNA ***,this bacterium was acid tolerant for hours at low ***,a total of 250(96.9%) genomic DNA samples of 258 biopsy specimens and DNA from 240 bacterial isolates were positive for the 613 bp amplicons by targetin

关键词： Antral biopsy Helicobacter pylori Pseudomonas fluorescens HSP60 Nested polymerase chain reaction Acid-tolerant bacteria

Assessment of Community Based Climate Change Risk Focusing Agriculture and Fisheries Sector in Haor Areas of Bangladesh

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Atmospheric and Climate Sciences 2021年第2期11卷 342-362页

作者： Ahmmed Zulfiqar Rahaman gopal chandra Sarker Bhuiya Md. Tamim Al Hossain Sadequr Rahman Bhuiyan A. S. M. Julker Naem Center for Environmental and Geographic Information Services (CEGIS) Dhaka Bangladesh Haor Infrastructure and Livelihood Improvement Project (HILIP) Local Government Engineering Department (LGED) Dhaka Bangladesh

The research paper aims at understanding the level of climate change risk of the Haor areas of Bangladesh. It follows a participatory approach, using Focus Group Discussion (FGD) and Key Informant Interview (KII) to identify important climate change induced hazards, assess the probability of occurrences of the hazards and level of their consequences. Using geo-spatial techniques, the paper prepares hazard risk maps and risk hotspot maps. Policy documents, previous researches, and Government statistics and reports helped to develop the concepts and planning of the research. The unparalleled hydro-ecological attributes of Haor areas pose both opportunities and constraints for the local population. Poverty, lack of basic infrastructure and amenities, awareness and external support have already put the people in Haor areas in a vulnerable situation while the recurring natural hazards and shifting pattern of climate are making the constraints nearly unmanageable. Excessive rainfall in the monsoon and drought in the dry season is affecting the farming and fishery-based communities the most. The community perceptions on hazards, their occurrences, consequences and relative importance of each hazard for the agriculture or fisheries sector in the study area have been collected from the FGDs and subsequently analyzed to produce individual and multi-hazard risk maps for the area based on scoring. This information is also used to rank the Upazillas in the study area depending on risk level. The community people were also asked to select the important elements or structural facilities at risk in their area needed for their life and livelihood. Based on this selection, risk hotspot map for the study area has been prepared using GIS based weighted overlay methods. The final risk hotspot map identifies about hundred unions in the area as hotspots. This paper might encourage the local government organizations to make choice on the interventi

关键词： Haor Climate Change Vulnerability Mapping Risk Assessment Participatory Methods GIS

Assessment of Community Based Climate Change Risk Focusing Agriculture and Fisheries Sector in Haor Areas of Bangladesh

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