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Prognosis and feasibility of en-bloc vascular resection in stage Ⅱ pancreatic adenocarcinoma 被引量:11
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作者 K Dilip chakravarty Jun-Te Hsu +3 位作者 Chun-Nan Yeh Ta-Sen Yeh Tsann-Long Hwang Miin-Fu Chen 《World Journal of Gastroenterology》 SCIE CAS CSCD 2010年第8期997-1002,共6页
AIM:To establish the prognosis and feasibility of en-bloc vascular resection of stage pancreatic adenocarcinoma of the head and uncinate process.METHODS:We retrospectively analyzed 87 patients with stage pancreatic ad... AIM:To establish the prognosis and feasibility of en-bloc vascular resection of stage pancreatic adenocarcinoma of the head and uncinate process.METHODS:We retrospectively analyzed 87 patients with stage pancreatic adenocarcinoma,who were subjected to pancreaticoduodenectomy (PD) and pylo-rus-preserving PD (PPPD) between 1996 and 2006 in Chang Gung Memorial Hospital,Taiwan. Twelve and 75 patients underwent PD/PPPD with and without resection of portal vein/superior mesenteric vein (PV/SMV),respectively.RESULTS:The overall 1-and 3-year survival rates of patients undergoing PD/PPPD with and without vas-cular resection were 50.0% and 16.7%,and 44.4% and 12.2%,respectively. Morbidity and mortality rates in the PV/SMV resection vs non-resection group were 50.0% and 0.0%,and 40.0% and 2.7%,respectively. In multivariate analysis,serum bilirubin,histological differentiation and adjuvant chemotherapy were independent prognostic factors that influenced survival.CONCLUSION:In stage adenocarcinoma of the pancreatic head and uncinate process,serum bilirubin,histological differentiation and adjuvant chemotherapy were independent prognostic factors,and en-bloc vascular resection is a feasible option in carefully selected patients. 展开更多
关键词 Pancreatic neoplasms ADENOCARCINOMA Portal vein Superior mesenteric vein Pancreaticoduo-denectomy CHEMOTHERAPY
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Mid-infrared silicon photonic waveguides and devices [Invited] 被引量:10
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作者 YI ZOU SWAPNAJIT chakravarty +2 位作者 CHI-JUI CHUNG XIAOCHUAN XU RAY T.CHEN 《Photonics Research》 SCIE EI 2018年第4期254-276,共23页
Silicon has been the material of choice of the photonics industry over the last decade due to its easy integration with silicon electronics, high index contrast, small footprint, and low cost, as well as its optical t... Silicon has been the material of choice of the photonics industry over the last decade due to its easy integration with silicon electronics, high index contrast, small footprint, and low cost, as well as its optical transparency in the nearinfrared and parts of mid-infrared(MIR) wavelengths(from 1.1 to 8 μm). While considerations of micro-and nano-fabrication-induced device parameter deviations and a higher-than-desirable propagation loss still serve as a bottleneck in many on-chip data communication applications, applications as sensors do not require similar stringent controls. Photonic devices on chips are increasingly being demonstrated for chemical and biological sensing with performance metrics rivaling benchtop instruments and thus promising the potential of portable, handheld,and wearable monitoring of various chemical and biological analytes. In this paper, we review recent advances in MIR silicon photonics research. We discuss the pros and cons of various platforms, the fabrication procedures for building such platforms, and the benchmarks demonstrated so far, together with their applications. Novel device architectures and improved fabrication techniques have paved a viable way for realizing low-cost, high-density,multi-function integrated devices in the MIR. These advances are expected to benefit several application domains in the years to come, including communication networks, sensing, and nonlinear systems. 展开更多
关键词 光电子产业 硅电子 发展现状 通讯技术
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Significant increase in HBV, HCV, HIV and syphilis infections among blood donors in West Bengal, Eastern India 2004-2005: Exploratory screening reveals high frequency of occult HBV infection 被引量:9
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作者 Prasun Bhattacharya Partha Kumar Chandra +6 位作者 Sibnarayan Datta Arup Banerjee Subhashish Chakraborty Krishnan Rajendran Subir Kumar Basu Sujit Kumar Bhattacharya Runu chakravarty 《World Journal of Gastroenterology》 SCIE CAS CSCD 2007年第27期3730-3733,共4页
AIM: To evaluate the prevalence of markers of hepatitis B virus (HBV) and hepatitis C virus (HCV) and human immunodeficiency virus (HIV) among blood donors in Kolkata, Eastern India for two consecutive years and to co... AIM: To evaluate the prevalence of markers of hepatitis B virus (HBV) and hepatitis C virus (HCV) and human immunodeficiency virus (HIV) among blood donors in Kolkata, Eastern India for two consecutive years and to conduct a pilot study to explore the presence of HBV DNA among hepatitis B surface antigen (HBsAg) negative but anti-HBc positive blood donors. METHODS: Seroprevalence of HBsAg, anti-HCV and anti-HIV was studied among 113 051 and 106 695 voluntary blood donors screened in 2004 and 2005, respectively. Moreover, a pilot study on 1027 HBsAg negative donors was carried out for evaluating the presence of HBV DNA by PCR on HBsAg negative/anti- HBc positive donors. RESULTS: A statistically significant increase in the prevalence of HBV (1448 vs 1768, P < 0.001), HIV (262 vs 374, P < 0.001), HCV (314 vs 372, P = 0.003) and syphilis (772 vs 853, P = 0.001) infections was noted among blood donors of Kolkata West Bengal in 2005 as compared to 2004. Moreover, the exploratory study on 1027 HBsAg negative donors revealed that 188 (18.3%)of them were anti-HBc positive out of which 21% were positive for HBV DNA. CONCLUSION: The findings of this study underscore the significantly increasing endemicity of hepatitis viruses, syphilis and HIV among the voluntary blood donors of our community. The pilot study indicates a high rate of prevalence of HBV DNA among HBsAg negative/anti-HBc positive donors and thus emphasizes the need for a more sensitive and stringent screening algorithm for blood donations. 展开更多
关键词 Hepatitis B virus Human immunodeficiency virus Hepatitis C virus Blood donation Occult HBV infection
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Changes in organic structure and mineral phases transformation of coal during heat treatment on laboratory scale 被引量:8
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作者 Vivek Mishra Mamta Sharma +1 位作者 Sanchita chakravarty Amit Banerjee 《International Journal of Coal Science & Technology》 EI 2016年第4期418-428,共11页
Structural changes due to coalification and oxidation influence the coal quality, geochemically and petrologically. Understanding of the coal structures helps to predict the behaviour of coal at various processes. The... Structural changes due to coalification and oxidation influence the coal quality, geochemically and petrologically. Understanding of the coal structures helps to predict the behaviour of coal at various processes. The objective of this paper is to study the changes in organic structure and mineral phase transformation during combustion. Different density fractions were generated and then heated at different temperatures from 200 to 1000 ℃. Petrography, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were carried out on all the density fractions aimed to accomplish this objective. Here, through petrography, it was observed that the vitrinite and liptinite macerals disappear at higher temperature while porous inertinite is seen. The inertinite structure is exposed which is assumed by the presence of -OH and C-O-C stretches with the aromatic nucleus (CH) and three to four adjacent H from FTIR spectra. Moreover, it can be concluded that aliphatic groups get collapsed at high temperature. In case of inorganic matter, through XRD and FTIR, it is also revealed that with increasing temperature, clay minerals converted into elemental oxides. Hence, this study is suggesting that the structures of coal are altered by the degree of contact metamorphism. 展开更多
关键词 COAL Heat treatment Oxidation PETROGRAPHY FTIR XRD
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Discrete element approach for mine dump stability analysis 被引量:8
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作者 RADHAKANTA Koner DEBASHISH chakravarty 《Mining Science and Technology》 EI CAS 2010年第6期809-813,共5页
Mine overburden dumps have posed significant safety issues in the operations of various unit operations of open pit min-ing especially the external dumps. The external dumps are composed of a mixture of fragmented roc... Mine overburden dumps have posed significant safety issues in the operations of various unit operations of open pit min-ing especially the external dumps. The external dumps are composed of a mixture of fragmented rocks and loose soil. Their charac-teristic is comparable to heavily discontinuous solid mass. The conventional approach of limit equilibrium methods provide safety factors for the slope but nothing about the stress-strain characteristics of the large dump mass. The designs of dump location and their respective geometry are integrated for the know-how of the stability characteristics of these dumps. The discrete element method uses a circular disk to represent the granular solid mass and their interactions are described by the Newton’s third law of motion. The displacement is described by the sliding of the circular disk. This work is focused on the modeling efficiency of the discrete element methods to represent the behaviour of mine dump masses with the specified joint plane for the limit equilibrium method. The advantage of the work lies on the ease of information retrieval at any point at the dump mass concerning the stress and strain histories, displacement, failures etc. which when integrated produces a better understanding of the stability of the dump masses. 展开更多
关键词 dump slope safety factor discrete element method micromechanical properties discontinuity plane
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Distribution of mineral species in different coal seams of Talcher coalfield and its transformation behavior at varying temperatures 被引量:4
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作者 Amit Banerjee P. R. Mishra +4 位作者 Ashok Mohanty K. chakravarty R. Das Biswas R. Sahu S. chakravarty 《International Journal of Coal Science & Technology》 EI 2016年第2期97-103,共7页
Mineral phase characterization and thorough understanding of its transformation behavior during combustion are imperative to know the potential utilization of coal in the thermal industries. The primary objective of t... Mineral phase characterization and thorough understanding of its transformation behavior during combustion are imperative to know the potential utilization of coal in the thermal industries. The primary objective of this work is to analyze the quality of Indian Coals and obtain their mineral species-specific information at different depths. The samples were obtained from Talcher Coalfield, Odisha, India. Coal from four seam sections in the Talcher coalfield, India are mainly high ash coal (〉50 %) and volatile matter deceases along with the seam depth. XRD results show that the major mineral phases present in the coal are quartz and kaolinite. Siderite, illite, and anatase were found in minor quantities. It has been observed that the clay minerals (kaolinite, silimanite, illite) decompose at higher temperature and traces of dolomite, mullite, hematite etc. are formed during the process of combustion. Among the four seams (M2, M12, M24 and M43) studied, ash of M43 has high A1203%, TIO2% and K20% content and low SIO2%, CaO% and MgO% content. High acid- to-base ratios contributed to high ash fusion temperatures (IDT 〉 1500 ℃) and low slagging potential of the coals studied. Relatively low fouling index (〈0.3) was estimated for all the coal seams studied. Furthermore, thermodynamic modeling software, FactSage, have been used to envision the mineral phase transformations that take place between 800 and 1500℃ during coal combustion. 展开更多
关键词 Proximate analysis - Ultimate analysis FactSage XRD AFT Talcher coalfield
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An analysis of energy consumption and carbon footprints of cryptocurrencies and possible solutions 被引量:1
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作者 Varun Kohli Sombuddha chakravarty +2 位作者 Vinay Chamola Kuldip Singh Sangwan Sherali Zeadally 《Digital Communications and Networks》 SCIE CSCD 2023年第1期79-89,共11页
There is an urgent need to control global warming caused by humans to achieve a sustainable future.CO_(2) levels are rising steadily,and while countries worldwide are actively moving toward the sustainability goals pr... There is an urgent need to control global warming caused by humans to achieve a sustainable future.CO_(2) levels are rising steadily,and while countries worldwide are actively moving toward the sustainability goals proposed during the Paris Agreement in 2015,we are still a long way to go from achieving a sustainable mode of global operation.The increased popularity of cryptocurrencies since the introduction of Bitcoin in 2009 has been accompanied by an increasing trend in greenhouse gas emissions and high electrical energy consumption.Popular energy tracking studies(e.g.,Digiconomist and the Cambridge Bitcoin Energy Consumption Index(CBECI))have estimated energy consumption ranges from 29.96 TWh to 135.12 TWh and 26.41 TWh to 176.98 TWh,respectively for Bitcoin as of July 2021,which are equivalent to the energy consumption of countries such as Sweden and Thailand.The latest estimate by Digiconomist on carbon footprints shows a 64.18 MtCO_(2) emission by Bitcoin as of July 2021,close to the emissions by Greece and Oman.This review compiles estimates made by various studies from 2018 to 2021.We compare the energy consumption and carbon footprints of these cryptocurrencies with countries around the world and centralized transaction methods such as Visa.We identify the problems associated with cryptocurrencies and propose solutions that can help reduce their energy consumption and carbon footprints.Finally,we present case studies on cryptocurrency networks,namely,Ethereum 2.0 and Pi Network,with a discussion on how they can solve some of the challenges we have identified. 展开更多
关键词 Blockchain Carbon footprint Climate change Cryptocurrency SUSTAINABILITY
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Physico-chemical and elemental investigation of aqueous leaching of high sulfur coal and mine overburden from Ledo coalfield of Northeast India 被引量:5
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作者 Madhulika Dutta Puja Khare +2 位作者 Sanchita chakravarty Durlov Saikia Binoy K. Saikia 《International Journal of Coal Science & Technology》 EI 2018年第3期265-281,共17页
Acid mine drainage (AMD) is one of the major problems in high sulfur coal mining areas generating acidic water. The acidic mine water generated contain hazardous elements in varying concentrations. The Northeastern ... Acid mine drainage (AMD) is one of the major problems in high sulfur coal mining areas generating acidic water. The acidic mine water generated contain hazardous elements in varying concentrations. The Northeastern Indian coalfield produces considerable amounts of AMD. The AMD and metal leaching from coal and mine over burden (OB) are the two important naturally occurring processes. In order to know the AMD potential, the aqueous leaching experiment of a few coal and OB samples from the Ledo colliery of the Northeastern coalfield, Mergherita (India), at different time periods (1, 3, 5, and 8 h) and at different temperatures (25, 45, 65, and 90℃) were performed in the laboratory. The physico- chemical analysis of the aqueous leachates shows the pH, electrical conductivity (EC), and total dissolved solid (TDS) in the range of 1.62-3.52, 106-2006 μs/cm, and 106-1003 ppm for the raw coal samples respectively. The OB samples produced pH, EC, and TDS in the range of 3.68-6.92, 48.6-480 μs/cm, and 69.5-240 ppm respectively. From the study, it was revealed that the concentrations of major (Si, A1, K, Na, Fe, Ca, Mg), minor (Mn) and trace/hazardous elements (As, Ba, Cd, Co, Cr, Cu, Hg, Ni, Pb, Se, Zn) considerably change with leaching time as well as with leaching temperature. Out of these elements As, Cd, Hg, Pb, Cr, and Se are of greater environmental importance. Alteration of the physico-chemical structure of the coal and OB samples resulting from leaching was also studied by field emission scanning electron microscope- energy-dispersive X-ray spectroscopy method. The release of the potentially hazardous elements from the raw coal and OB during leaching time periods to the leachates was detected by inductively coupled plasma-atomic emission spectroscopy and ion-chromatographic analyses. The major minerals found in coal and OB are quartz (SiO2), pyrite (FeS2), hematite, marcasite, and kaolinite. The association of different functional groups in minerals and their mode 展开更多
关键词 AMD High sulfur coal Coal mine overburden Aqueous leaching Elements in coal and OB Coal qualityassessment
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Development of a mass model in estimating weight-wise particle size distribution using digital image processing 被引量:4
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作者 Maiti Abhik chakravarty Debashish +1 位作者 Biswas Kousik Halder Arpan 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2017年第3期435-443,共9页
Particle size distribution of coarse aggregates through mechanical sieving gives results in terms of cumu- lative mass percent. But digital image processing generated size distribution of particles, while being fast a... Particle size distribution of coarse aggregates through mechanical sieving gives results in terms of cumu- lative mass percent. But digital image processing generated size distribution of particles, while being fast and accurate, is often expressed in terms of area function or number of particles. In this paper, a mass model is developed which converts the image obtained size distribution to mass-wise distribution, mak- ing it readily comparable to mechanical sieving data. The concept of weight/particle ratio is introduced for mass reconstruction from 2D images of particle aggregates. Using this mass model, the effects of several particle shape parameters (such as major axis, minor axis, and equivalent diameter) on sieve-size of the particles is studied. It is shown that the sieve-size of a particle strongly depend upon the shape param- eters, 91% of its variation being explained by major axis, minor axis, bounding box length and equivalent diameter. Furthermore, minor axis gives an overall accurate estimate of particle sieve-size, error in mean size (D-50) being just 0.4%. However, sieve-size of smaller particles (〈20 ram) strongly depends upon the length of the smaller arm of the bounding box enclosing them and sieve-sizes of larger particles (〉20 mm) are highly correlated to their equivalent diameters. Multiple linear regression analysis has been used to generate overall mass-wise particle size distribution, considering the influences of all these shape parameters on particle sieve-size. Multiple linear regression generated overall mass-wise particle size distribution shows a strong correlation with sieve generated data. The adjusted R-square value of the regression analysis is found to be 99 percent (w.r,t cumulative frequency). The method proposed in this paper provides a time-efficient way of producing accurate (up to 99%) mass-wise PSD using digital image processing and it can be used effectively to renlace the mechanical sieving. 展开更多
关键词 Particle size distribution Image analysis Particle shape parameters Weight/particle ratio Sieve analysis
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A deep neural network regressor for phase constitution estimation in the high entropy alloy system Al-Co-Cr-Fe-Mn-Nb-Ni
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作者 G.Vazquez S.chakravarty +1 位作者 R.Gurrola R.Arróyave 《npj Computational Materials》 SCIE EI CSCD 2023年第1期1661-1674,共14页
High Entropy Alloys(HEAs)are composed of more than one principal element and constitute a major paradigm in metals research.The HEA space is vast and an exhaustive exploration is improbable.Therefore,a thorough estima... High Entropy Alloys(HEAs)are composed of more than one principal element and constitute a major paradigm in metals research.The HEA space is vast and an exhaustive exploration is improbable.Therefore,a thorough estimation of the phases present in the HEA is of paramount importance for alloy design.Machine Learning presents a feasible and non-expensive method for predicting possible new HEAs on-the-fly.A deep neural network(DNN)model for the elemental system of:Mn,Ni,Fe,Al,Cr,Nb,and Co is developed using a dataset generated by high-throughput computational thermodynamic calculations using Thermo-Calc.The features list used for the neural network is developed based on literature and freely available databases.A feature significance analysis matches the reported HEAs phase constitution trends on elemental properties and further expands it by providing so far-overlooked features.The final regressor has a coefficient of determination(r^(2))greater than 0.96 for identifying the most recurrent phases and the functionality is tested by running optimization tasks that simulate those required in alloy design.The DNN developed constitutes an example of an emulator that can be used in fast,real-time materials discovery/design tasks. 展开更多
关键词 ALLOY NEURAL network
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Anti-viral role of toll like receptor 4 in hepatitis B virus infection: An in vitro study 被引量:4
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作者 Dipanwita Das Neelakshi Sarkar +7 位作者 Isha Sengupta Ananya Pal Debraj Saha Manikankana Bandopadhyay Chandrima Das Jimmy Narayan Shivram Prasad Singh Runu chakravarty 《World Journal of Gastroenterology》 SCIE CAS 2016年第47期10341-10352,共12页
AIM Toll like receptors plays a significant anti-viral role in different infections. The aim of this study was to look into the role of toll like receptor 4(TLR4) in hepatitis B virus(HBV) infection.METHODS Real time ... AIM Toll like receptors plays a significant anti-viral role in different infections. The aim of this study was to look into the role of toll like receptor 4(TLR4) in hepatitis B virus(HBV) infection.METHODS Real time PCR was used to analyze the transcription of TLR4 signaling molecules, cell cycle regulators and HBV DNA viral load after triggering the Hep G2.2.15 cells with TLR4 specific ligand. Nuclear factor(NF)-κB translocation on TLR4 activation was analyzed using microscopic techniques. Protein and cell cycle analysis was done using Western Blot and FACS respectively.RESULTS The present study shows that TLR4 activation represses HBV infection. As a result of HBV suppression, there are several changes in host factors which include partial release in G1/S cell cycle arrest and changes in host epigenetic marks. Finally, it was observed that anti-viral action of TLR4 takes place through the NF-κB pathway.CONCLUSION The study shows that TLR4 activation in HBV infection brings about changes in hepatocyte microenvironment and can be used for developing a promising therapeutic target in future. 展开更多
关键词 Hepatitis B virus Toll like receptor 4 Cell cycle Epigenetic marks Innate immune response
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Quantification of organic carbon and primary nutrients in litter and soil in a foothill forest plantation of eastern Himalaya 被引量:4
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作者 Gopal Shukla Nazir A. Pala Sumit chakravarty 《Journal of Forestry Research》 SCIE CAS CSCD 2017年第6期1190-1197,共8页
The present study was an effort to understand the amount of litter fall and its subsequent decomposition and quantify the release of available nutrients and soil physicochemical characteristics in plantations of four ... The present study was an effort to understand the amount of litter fall and its subsequent decomposition and quantify the release of available nutrients and soil physicochemical characteristics in plantations of four forest tree species(Lagerstroemia parviflora, Tectona grandis, Shorea robusta and Michelia champaca) in the Chilapatta Reserve Forest of the Cooch Behar Wildlife Division in the Terai zone of West Bengal, India. The most litter(5.61 Mg ha)was produced by T. grandis plantation and the least(4.72 Mg ha) by L. parviflora. The material turnover rate to the soil through decomposition from total litter was fastest during the first quarter of the year and subsequently decreased during the next two quarters. The material turnover rate was only 1 year, which indicates that more than90% of the total litter produced decomposed within a year.The available primary nutrient content in litter varied across the four plantations over the year. The plantations generally did not significantly influence the soil physical characteristics but did significantly influence the availability of primary nutrients and organic carbon at two depths(1–15 and16–30 cm) over the year. The availability of soil primary nutrients in the four plantations also increased gradually from the first quarter of the year to the third quarter and then decreased during the last quarter to the same level as in the first quarter of the year at both depths. The availability for soil organic carbon in the plantations followed a similar trend. The amount of litter produced and the material turnover in the soil in the different plantations differed, influencing the nutrient availability and organic carbon at the plantations. The amount of soil organic carbon was highest for T. grandis(2.52 Mg ha) and lowest for L. parviflora(2.12 Mg ha). Litter is the source of soil organic matter,and more the litter that is produced by the plantations, the higher will be the content and amount of soil organic carbon in the plantation. 展开更多
关键词 Litter production DECOMPOSITION Organic carbon Material turnover Eastern Himalayas
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Thermal Decomposition Behavior and Kinetic Study of Jamadoba Coal and Its Density Separated Macerals: A Non-Isothermal Approach 被引量:1
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作者 Deepak Chandra Sau Amit Banerjee +3 位作者 Sanchita chakravarty Pragyan Senapati Rabiranjan Murmu Harekrushna Sutar 《Advances in Chemical Engineering and Science》 2021年第3期203-227,共25页
This kinetic study focuses on determining the thermal gravimetric profile of a particular grade of Indian sub-bituminous coal. A thermogravimetric analyzer (TGA-1000) was employed to investigate the thermal behavior a... This kinetic study focuses on determining the thermal gravimetric profile of a particular grade of Indian sub-bituminous coal. A thermogravimetric analyzer (TGA-1000) was employed to investigate the thermal behavior and extract the kinetic parameters of Jamadoba coal and its corresponding density sepa<span style="font-family:Verdana;color:#000000;">rated macerals. The weight loss was measured in air atmosphere. The coal </span><span style="font-family:Verdana;color:#000000;">samples used in this study were obtained from Jamadoba mines, Jharkhand. Sam</span><span style="font-family:Verdana;color:#000000;">ples of 35 mg and 200 μm mean size were subjected to synthetic air atmos</span><span style="font-family:Verdana;color:#000000;">pheres (21% O</span><sub><span style="font-family:Verdana;color:#000000;">2</span></sub><span style="font-family:Verdana;color:#000000;">). Heating rates of 2, 5 and 7</span><span style="font-family:;" "=""><span style="color:#000000;font-family:Verdana;">°</span><span style="font-family:Verdana;color:#000000;"></span><span><span style="font-family:Verdana;color:#000000;">C/min were applied until the tempera</span><span style="font-family:Verdana;color:#000000;">ture reached 1400</span></span><span><span style="color:#000000;font-family:Verdana;">°</span><span style="font-family:Verdana;color:#000000;">C, which was kept constant until burnout. Low heating</span></span><span><span style="font-family:Verdana;color:#000000;"> rate was preferred so that devolatilization occurs prior to ignition and </span><span style="font-family:Verdana;color:#000000;">combust</span><span style="font-family:Verdana;color:#000000;">ion. Derivative thermogravimetry (DTG) analysis method was applied to </span><span style="font-family:Verdana;color:#000000;">measure the weight changes and rates of weight loss used for calculating the kinetic parameters. The activation energy (</span><i><span style="font-family:Verdana;color:#000000;">E</span><sub><span style="font-family:Verdana;color:#000000;">a</span></sub 展开更多
关键词 Thermal Decomposition Kinetic Study Jamadoba Coal NON-ISOTHERMAL
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雾化治疗中气溶胶在深层肺泡输运特性的数值模拟
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作者 唐浦 Aranyak chakravarty +1 位作者 Neelesh A.PATANKAR 匡波 《医用生物力学》 CAS CSCD 北大核心 2022年第4期644-649,共6页
目的基于计算流体动力学的方法,模拟计算单个肺泡中的气体与气溶胶颗粒输运情况,研究深层肺泡内气体流动和气溶胶颗粒输运特性。方法采用一端有周期性扩张/收缩半球形壁的长直导管作为单一肺泡及肺泡管的简化近似,建立二维数学模拟模型... 目的基于计算流体动力学的方法,模拟计算单个肺泡中的气体与气溶胶颗粒输运情况,研究深层肺泡内气体流动和气溶胶颗粒输运特性。方法采用一端有周期性扩张/收缩半球形壁的长直导管作为单一肺泡及肺泡管的简化近似,建立二维数学模拟模型。考虑呼吸气体在半球边界上的扩散,采用欧拉-欧拉方法对肺泡管中气体以及气溶胶颗粒的输运方程进行求解。结果整个呼吸过程中,管道中空气的成分比率以稳定的周期方式随时间变化。气溶胶在管道输运主要依赖于颗粒的扩散系数,平流输运只有微小的影响。气溶胶颗粒尺寸减小时,气溶胶的扩散速度与深度均有提高,粒径小于4μm时该现象尤为明显,且呼吸频率和幅度的增大可以显著提升颗粒的输运能力。结论雾化治疗中,粒径较小的气溶胶颗粒可以增强药物扩散速度。深呼吸有助于提升颗粒的输运效果,治疗中应鼓励患者深呼吸。 展开更多
关键词 雾化疗法 深层肺泡模型 气溶胶输运 欧拉-欧拉方法 数值模拟 动网格
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Distribution of hepatitis B virus genotypes:Phylogenetic analysis and virological characteristics of Genotype C circulating among HBV carriers in Kolkata,Eastern India 被引量:3
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作者 Arup Banerjee Sibnarayan Datta +3 位作者 Partha K Chandra Susanta Roychowdhury Chinmoy Kumar Panda Runu chakravarty 《World Journal of Gastroenterology》 SCIE CAS CSCD 2006年第37期5964-5971,共8页
AIM: To evaluate the genotype distribution of hepatitis B virus (HBV) in Eastern India and to clarify the phyloge- netic origin and virological characteristics of the recently identifi ed genotype C in this region. ME... AIM: To evaluate the genotype distribution of hepatitis B virus (HBV) in Eastern India and to clarify the phyloge- netic origin and virological characteristics of the recently identifi ed genotype C in this region. METHODS: Genotype determination, T1762/A1764 mutation in the basal core promoter (BCP) and A1896 mutation in the precore region of 230 subjects were de- termined by restriction fragment length polymorphism method (RFLP) and the result was confi rmed by direct sequencing. RESULTS: The predominant genotypes D (HBV/D) and A (HBV/A) were detected in 131/230 (57%) and 57/230 (25%) samples. In addition, genotype C (HBV/C) was detected in 42/230 (18%) isolates. Surface gene region was sequenced from 45 isolates (27 HBV/C, 9 HBV/A and 9 HBV/D). Phylogenetic analysis revealed that all of the HBV/C sequences clustered with South East Asian subgenotype (HBV/Cs). The sequence data showed re- markable similarity with a Thai strain (AF068756) (99.5% ± 0.4% nucleotide identities) in 90% of the genotype C strains analyzed. T1762/A1764 mutation in BCP re- gion, associated with high ALT was signifi cantly higher in HBeAg negative isolates than HBeAg positive isolates. Frequency of A1896 mutation leading to HBeAg negativ- ity was low.CONCLUSION: The present study reports the genotypic distribution and the characteristics of partial genome sequences of HBV/C isolates from Eastern India. Low genetic diversity and confi nement of HBV/C in Eastern India possibly indicate a recent, limited, spread in this region. Genotype C with T1762/A1764 mutation has been reported to increase the risk for hepatocellular car- cinoma; therefore genotype C carriers in Eastern India should be carefully monitored. 展开更多
关键词 HBV genotypes HBV/Cs Eastern India T1762/A1764 mutation
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Design of crown pillar thickness using finite element method and multivariate regression analysis 被引量:3
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作者 Kumar Hemant Deb Debasis chakravarty D. 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2017年第6期955-964,共10页
Minerals are now being extracted from deep mines due to drying up of resource in shallow ground. The need for suitable supports and ground control mechanisms for safe mining necessitates proper pillar design with fill... Minerals are now being extracted from deep mines due to drying up of resource in shallow ground. The need for suitable supports and ground control mechanisms for safe mining necessitates proper pillar design with filling technology. In addition, high horizontal stress may cause collapse of hanging wall and footwall rocks, hence designing of suitable crown pillars is absolutely necessary for imposing overall safety of the stopes. This paper provides a methodology for the evaluation of the required thickness of crown pillars for safe operation at depth ranging from 600 m to 1000 m. Analyses are conducted with the results of 108 non-linear numerical models considering Drucker-Prager material model in plane strain condition. Material properties of ore body rock and thickness of crown pillars are varied and safety factors of pillars estimated. Then, a generalized statistical relationship between the safety factors of crown pillars with the various input parameters is developed. The developed multivariate regression model is utilized for generating design/stability charts of pillars for different geo-mining conditions.These design charts can be used for the design of crown pillar thickness with the depth of the working,taking into account the changes of the rock mass conditions in underground metal mine. 展开更多
关键词 CUT and FILL mining CROWN PILLAR FEM Regression model DESIGN CHART
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Existence of spatiotemporal patterns in the reaction-diffusion predator-prey model incorporating prey refuge 被引量:3
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作者 Lakshmi Narayan Guin Benukar Mondal Santabrata chakravarty 《International Journal of Biomathematics》 2016年第6期87-111,共25页
The pattern formation in reaction-diffusion system has long been the subject of interest to the researchers in the domain of mathematical ecology because of its universal exis- tence and importance. The present invest... The pattern formation in reaction-diffusion system has long been the subject of interest to the researchers in the domain of mathematical ecology because of its universal exis- tence and importance. The present investigation deals with a spatial dynamics of the Beddington-DeAngelis predator-prey model in the presence of a constant proportion of prey refuge. The model system representing boundary value problem under study is subjected to homogeneous Neumann boundary conditions. The asymptotic stability including the local and the global stability and the bifurcation as well of the unique pos- itive homogeneous steady state of the corresponding temporal model has been analyzed. The Turing instability region in two-parameter space and the condition of diffusion- driven instability of the spatiotemporal model are investigated. Based on the appro- priate numerical simulations, the present model dynamics in Turing space appears to get influenced by prey refuge while it exhibits diffusion-controlled pattern formation growth to spots, stripe-spot mixtures, labyrinthine, stripe-hole mixtures and holes repli- cation. The results obtained appear to enrich the findings of the model system under consideration. 展开更多
关键词 Beddington DeAngelis functional response prey refuge STABILITY reaction-diffusion predator-prey model spatiotemporal pattern.
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Numerical analysis of rainfall effects in external overburden dump 被引量:3
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作者 Radhakanta Koner Debashish chakravarty 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2016年第5期825-831,共7页
The effect of slope angle for external overburden dump in response to average and heavy rainfall has been analyzed using a two dimensional finite difference method of transient water flow through unsaturated–saturate... The effect of slope angle for external overburden dump in response to average and heavy rainfall has been analyzed using a two dimensional finite difference method of transient water flow through unsaturated–saturated soil. The external dump stability is evaluated for five geomaterial types on the basis of globally accepted safety factor analysis technique, based on shear strength reduction approach using finite difference method. The results obtained from the finite difference method of analysis indicate that the external dump with more than 30° slope angle is greatly influenced by the rainfall under the studied conditions for geomaterial 3, 4 and 5, whereas dumps with geomaterial 1 and 2 remain safe. The analysis shows that major slope failure is out of preview for the studied rainfall conditions. 展开更多
关键词 External overburden dumps Shear strength reduction Finite difference approach RAINFALL STABILITY
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非石油资源补强填充剂Shungit用于轮胎和橡胶制品的研究
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作者 A. chakravarty S. N. chakravarty 吕百龄 《橡胶科技》 2008年第15期18-24,共7页
关键词 白炭黑 补强填充剂 门尼粘度 拉伸强度 定伸应力 胶料 橡胶制品 伸长率 胎面胶 门尼焦烧时间
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Blood and CSF biomarkers for post-stroke epilepsy:a systematic review 被引量:1
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作者 Priya Dev Mareena Cyriac +1 位作者 Kamalesh chakravarty Abhishek Pathak 《Acta Epileptologica》 2022年第3期127-135,共9页
Post-stroke epilepsy is a common complication of ischemic stroke which adversely affects the prognosis of patients.Clinical and radiological parameters cannot adequately predict the risk.Therefore,the discovery of bio... Post-stroke epilepsy is a common complication of ischemic stroke which adversely affects the prognosis of patients.Clinical and radiological parameters cannot adequately predict the risk.Therefore,the discovery of biomarkers is imperatively needed for predicting post-stroke epilepsy.We conducted a systematic review of diagnostic and prognostic biomarkers for post-stroke epilepsy through a comprehensive literature search in different databases.All articles that met our inclusion criteria were assessed for quality using the modified Quality Assessment of Diagnostic Accuracy Studies questionnaire.Eight eligible studies were included in this systematic review.Out of 22 assessed biomarkers,nine biomarkers showed significant association with post-stroke epilepsy.The T allele of CD40(cluster of differentiation 40)−1C/T polymorphism,the CC genotype of TRPM6(transient receptor potential cation channel subfamily M member 6)rs2274924,the allele polymorphism of MAD2(mitochondrial aldehyde dehydrogenase 2),the mRNA level of interleukin-6(IL-6),the plasma level of endostatin,and the mRNA expression of IL-1βshow a positive correlation with post-stroke epilepsy;while S100 calcium-binding protein B,heat shock 70 kDa protein-8 and neuropeptide Y are inversely associated with post-stroke epilepsy.As a small number of patients were recruited,further studies are needed to confirm their potential use for predicting post-stroke epilepsy. 展开更多
关键词 Post-stroke epilepsy BIOMARKER STROKE Blood and CSF biomarker Systematic review
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