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Search Results: 1 - 10 of 22657 matches for " Dilip Kumar Saha "
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Crystallization, Transport and Magnetic Properties of the Amorphous (Fe1–xMnx)75P15C10 Alloys  [PDF]
Md. Kamruzzaman, Md. Abu Sayem Karal, Dilip Kumar Saha, Feroz Alam Khan
Journal of Crystallization Process and Technology (JCPT) , 2012, DOI: 10.4236/jcpt.2012.23013
Abstract: The amorphous (Fe1-xMnx)75P15C10 (0 ≤ x ≥ 0.30) alloys were prepared by the standard melt spinning technique and investigated their crystallization, thermal, transport and magnetic properties. Crystallization was observed from 400℃ to 650℃ with an interval 50℃within 30 minutes annealing time by XRD. The as-cast samples were amorphous in nature. Annealing 400℃ to 450℃ samples showed the mixed bcc Fe and amorphous structures. The lattice parameter ‘a’ was varied from 2.855 to 2.859 ? but above 450℃, samples contained hexagonal, FeP and FeC structures. The lattice parameters ‘a’ and ‘c’ were varied from (5.016-5.036) ? and (13.575-13.820) ? , respectively. Average crystallite size was found to vary from 8 to 48 nm. Crystallization temperature and weight change were observed by differential thermal analysis and thermogravimetric analysis, respectively. Crystallization temperature was increased with increasing Mn content. Resistivity was increased above and bellows the Curie temperature. Real permeability remained almost constant upto around 106 Hz for of all samples after that it was decreased with increasing frequency and it was also decreased with Mn, whereas imaginary permeability was increased sharply above frequency 107 Hz. The value of saturation magnetization was found to decrease with increment Mn.
Targeting Estrogen Receptor Sites in Human Breast Cancer Cell Line T47D With Copper Conjugates of Nonsteriodal Anti-inflammatory Drug Derivatives: Antiproliferative Activityof Ketoprofen Derivative and its Copper Complex
Dilip Kumar Saha,Shreelekha Padhye,Subhash Padhye
Metal-Based Drugs , 2001, DOI: 10.1155/mbd.2001.73
Abstract:
Confronting the Galactic Center Gamma Ray Excess With a Light Scalar Dark Matter
Dilip Kumar Ghosh,Subhadeep Mondal,Ipsita Saha
Physics , 2014, DOI: 10.1088/1475-7516/2015/02/035
Abstract: The Fermi Large Area Telescope observed an excess in gamma ray emission spectrum coming from the center of the Milky Way galaxy. This data reveals that a light Dark Matter (DM) candidate of mass in the range 31-40 GeV, dominantly decaying into $b\bar b$ final state, can explain the presence of the observed bump in photon energy. We try to interpret this observed phenomena by sneutrino DM annihilation into pair of fermions in the Supersymmetric Inverse Seesaw Model (SISM). This model can also account for tiny non-zero neutrino masses satisfying existing neutrino oscillation data. We show that a Higgs portal DM in this model is in perfect agreement with this new interpretation besides satisfying all other existing collider, cosmological and low energy experimental constraints.
Synthesis, Structural and Physical Properties of Cu1–xZnxFe2O4 Ferrites  [PDF]
Shahida Akhter, Deba Prasad Paul, Md. Abdul Hakim, Dilip Kumar Saha, Md. Al-Mamun, Alhamra Parveen
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.211223
Abstract: Zn substituted Cu-Zn ferrites with a composition Cu1-xZnxFe2O4 have been synthesized by standard double sintering ceramic method and characterized by X-ray diffraction. The single-phase cubic spinel structure of all the samples has been confirmed from X-ray diffraction analyses. The lattice constant is found to increase linearly with the manganese content obeying Vegard’s law. This increase in lattice parameter is explained in terms of the sizes of component ions. It is well known that density plays a key role in controlling the properties of polycrystalline ferrites. The X-ray and bulk densities of the Cu-Zn ferrite is significantly decreased whereas porosity increased with increasing Zn concentration, thereby giving an impression that zinc might be helping in the densification of the materials. SEM micrographs exhibit a decrease in grain size with increasing Zn content. The real part of initial permeability, μ′ increase with increasing Zn contents upto x = 0.5 after that it decreases with higher Zn content.
Effect of Sintering Temperature on Structural and Magnetic Properties of Ni0.55Zn0.45Fe2O4 Ferrites  [PDF]
Robiul Islam, Md Obaidur Rahman, M. Abdul Hakim, Dilip Kumar Saha, Saiduzzaman Saiduzzaman, Saroaut Noor, Md Al-Mamun
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.35048
Abstract: The effect of frequency and sintering temperature on initial permeability of Ni0.55Zn0.45Fe2O4 ferrites have been studied by using an impedance analyzer. The samples were prepared by conventional double sintering ceramic technique using oxide nanoparticles of grain size 30 - 50 nm. Single phase spinal structure has been confirmed for the prepared samples by X-ray diffraction. As the sintering temperatures increase from 1160℃ to 1300℃, the permeability gradually increases. The increase of permeability is ascribed to the increase of density and grain size. Grain size is expected to grow with the increase of sintering temperature. Ferrites with large average grain size posses higher initial permeability. The Curie temperatures determined from temperature dependence of permeability of the samples sintered at different temperatures are found to be Tc = (321 ± 1)℃ and independent of sintering temperature. At Ts = 1300℃, Tc is found to increase substantially which can be explained by the fact that Zn has evaporated from the surface layer.
Thermal Behavior and Magnetic Properties of Nd-Fe-B Based Exchange Spring Nanocomposites Nd4-xTbxFe83.5Co5Cu0.5Nb1B6 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) Melt-Spun Ribbons  [PDF]
Palash Chandra Karmaker, Mohammad Obaidur Rahman, Nguyen Huy Dan, Samia Islam Liba, Per Nordblad, Dilip Kumar Saha, Sheikh Manjura Hoque
Advances in Materials Physics and Chemistry (AMPC) , 2017, DOI: 10.4236/ampc.2017.76018
Abstract: Co-rich Nd-Fe-B nanocomposite ribbons with Tb substituted have been fabricated by single roller melt spinning technique of Nd4-xTbxFe83.5Co5Cu0.5Nb1B6 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) alloys in an argon (Ar) atmosphere at a circumferential speed of 40 m/s. According to the differential scanning calorimeter (DSC) traces the nanocomposite samples have been annealed at different temperatures like 675°C, 687°C, 700°C, 712°C and 725°C for 10 min. Crystallization behavior was studied by X-ray diffraction in which it was found that the XRD patterns are characterized by broad diffused pattern which demonstrate the amorphous state of materials. The ribbon samples were also characterized by vibration sample magnetometer (VSM) and Mössbauer spectroscopy at as-cast and annealed condition. Co-rich and Tb substitution has significantly enhanced the value of coercivity (Hc) and maximum energy product (BH)max. Highest value of Hc and (BH)max has been obtained as 2.36 kOe and 6.11 MGOe for the sample annealed at 700°C for 10 min with higher concentration of Tb. The M-H hysteresis loops show extremely soft natures which do not possess any area. We have found reduced remanent ratio (Mr/Ms) up to 0.49 at optimal annealing temperature 700°C. However, with the annealing of the samples in the above mentioned temperature, evolution of large coercivity was observed due to the formation of exchange couple hard and soft nanocrystal composites. We have investigated the variation of Curie temperature (Tc) with annealing temperature of the melt spun ribbon samples. Mossbauer spectroscopy was carried out to study the hyperfine parameters such as hyperfine field, hyperfine field distribution for full width half maximum (FWHM) and isomer shift of Fe species of these two phases.
On Detecting Sudden Changes in the Unconditional Volatility of a Time Series  [PDF]
Dilip Kumar
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.62028
Abstract: The present study highlights the drawback of using Sanso, Arago and Carrion’s (2004) AIT-ICSS algorithm in detecting sudden changes in the unconditional volatility when long memory is present in volatility. Simulation experiments show that the AIT-ICSS test is severely oversized and exhibits low power when long memory is present in volatility.
Weighted Bootstrap Approach for the Variance Ratio Tests: A Test of Market Efficiency  [PDF]
Dilip Kumar
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.63048
Abstract: By means of Monte Carlo experiments using the weighted bootstrap, we evaluate the size and power properties in small samples of Chow and Denning’s [1] multiple variance ratio test and the automatic variance ratio test of Choi [2]. Our results indicate that the weighted bootstrap tests exhibit desirable size properties and substantially higher power than corresponding conventional tests.
On Volatility Transmission from Crude Oil to Agricultural Commodities  [PDF]
Dilip Kumar
Theoretical Economics Letters (TEL) , 2017, DOI: 10.4236/tel.2017.72009
Abstract: The paper examines volatility transmission from crude oil market to agricultural commodities like wheat, corn, cotton and soybeans. We find that the volatility transmission from crude oil to agricultural commodities exhibits sudden changes over a study period. We also examine whether the sudden changes in volatility influence the observed sudden changes in volatility transmission from crude oil to agricultural commodities. Our results indicate the observed sudden change in volatility transmission mechanism is not influenced by sudden changes in volatility series.
Factors Impacting the Interest Rate Derivatives Usage in Indian Commercial Banks  [PDF]
Dilip Kumar
Theoretical Economics Letters (TEL) , 2017, DOI: 10.4236/tel.2017.73045
Abstract: In this paper, we examine the impact of interest rate risk factors on the interest rate derivatives (IRD) usage by commercial banks in India. We focus our analysis during the period 2008-2010. We have taken this period to highlight that during and after global financial crisis, what were the main factors that influence the interest rate derivatives usage by Indian commercial banks. We have used simulation analysis and regression analysis to identify the interest rate risk factors. Using Tobit fixed effect analysis, we are able to provide empirical evidence that interest rate risk drives the derivatives usages by Indian commercial banks. Our results indicate that asset size, the impact of interest rate shock on equity capital are positively related to use of derivatives for hedging as well as trading and interest rate sensitivity factor is negatively related to the use of derivatives for hedging and trading. New generation private banks have relatively large exposure to derivatives for trading purpose.
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