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M. S. Anwar,Shalendra Kumar,Faheem Ahmed,Nishat Arshi,G. W. Kim,C. G. Lee,Bon Heun Koo 한국자기학회 2011 Journal of Magnetics Vol.16 No.4
In this paper, magnetic property and magnetocaloric effect (MCE) in perovskite manganites of the type La(0.75-X)CeXCa0.25MnO3 (x = 0.0, 0.2, 0.3 and 0.5) synthesized by using the standard solid state reaction method have been reported. From the magnetic measurements as a function of temperature and applied magnetic field, we have observed that the Curie temperature (TC) of the prepared samples strongly dependent on Ce content and was found to be 255, 213 and 150 K for x = 0.0, 0.2 and 0.3, respectively. A large magnetocaloric effect in vicinity of TC has been observed with a maximum magnetic entropy change (|ΔSM|max) of 3.31 and 6.40 J/kgK at 1.5 and 4 T, respectively, for La0.55Ce0.2Ca0.25MnO3. In addition, relative cooling power (RCP) of the sample under the magnetic field variation of 1.5 T reaches 59 J/kg. These results suggest that La0.55Ce0.2Ca0.25MnO3 compound could be a suitable candidate as working substance in magnetic refrigeration at 213 K.
Water Vapor Adsorption and Hydrogen Peroxide Decomposition on Date Pit Carbonization Products
A.M. Youssef,Th. El-Nabarawy,S.A. Sayed Ahmed,W.E. Rashwan 한국탄소학회 2005 Carbon Letters Vol.6 No.4
Carbonization products C1, C2, C3, C4 and C5 were prepared by the carbonization of date pit in limited air, at 500, 600, 700, 800 and 1000℃, respectively. C1-V-600, C3-V-600, C1-V-1000 and C3-V-1000 were prepared by thermal treatment of C1 and C3 under vacuum at 600 and 1000℃. The textural properties were determined from nitrogen adsorption at 77 K and from carbon dioxide adsorption at 298 K. The surface pH, the FTIR spectra and the acid and base neutralization capacities of some carbons were investigated. The amounts of surface oxygen were determined by out-gassing the carbon-oxygen groups on the surface as CO2 and CO. The adsorption of water vapor at 308 K on C1, C2, C3 and C4 was measured and the decomposition of H2O2 at 308 K was also investigated on C1, C2, C3, C4 and C5. The surface area and the total pore volume decreased with the rise of the carbonization temperature from 500 to 1000℃. The adsorption of water vapor is independent on the textural properties, while it is related to the amount of acidic carbon-oxygen groups on the surface. The catalytic activity of H2O2 decomposition does not depend on the textural properties, but directly related to the amount of basic carbon-oxygen complexes out-gassed as CO, at high temperatures.
Poulose, Anesh Manjaly,Elnour, Ahmed Yagoub,Anis, Arfat,Shaikh, Hamid,Al-Zahrani, S.M.,George, Justin,Al-Wabel, Mohammad I.,Usman, Adel R.,Ok, Yong Sik,Tsang, Daniel C.W.,Sarmah, Ajit K. Elsevier 2018 The Science of the total environment Vol.619 No.-
<P><B>Abstract</B></P> <P>The application of biochar (BC) as a filler in polymers can be viewed as a sustainable approach that incorporates pyrolysed waste based value-added material and simultaneously mitigate bio-waste in a smart way. The overarching aim of this work was to investigate the electrical, mechanical, thermal and rheological properties of biocomposite developed by utilizing date palm waste-derived BC for the reinforcing of polypropylene (PP) matrix. Date palm waste derived BC prepared at (700 and 900°C) were blended at different proportions with polypropylene and the resultant composites (BC/PP) were characterized using an array of techniques (scanning electron microscope, energy-dispersive X-ray spectroscopy and Fourier transform infra-red spectroscopy). Additionally the thermal, mechanical, electrical and rheological properties of the BC/PP composites were evaluated at different loading of BC content (from 0 to15% w/w). The mechanical properties of BC/PP composites showed an improvement in the tensile modulus while that of electrical characterization revealed an enhanced electrical conductivity with increased BC loading. Although the BC incorporation into the PP matrix has significantly reduced the total crystallinity of the resulted composites, however; a positive effect on the crystallization temperature (T<SUB>c</SUB>) was observed. The rheological characterization of BC/PP composites revealed that the addition of BC had minimal effect on the storage modulus (G′) compared to the neat (PP).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Date palm waste derived biochar was used as filler for polymer composites' applications. </LI> <LI> Biochar/polypropylene (BC/PP) composites' properties such as electrical, mechanical, thermal and rheological were investigated. </LI> <LI> The BC/PP composites' surface resistivity was decreased by four orders of magnitude. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Ultrashort PW laser pulse interaction with target and ion acceleration
Ter-Avetisyan, S.,Singh, P.K.,Kakolee, K.F.,Ahmed, H.,Jeong, T.W.,Scullion, C.,Hadjisolomou, P.,Borghesi, M.,Bychenkov, V. Yu. Elsevier 2018 Nuclear Instruments & Methods in Physics Research. Vol.909 No.-
<P><B>Abstract</B></P> <P>We present the experimental results on ion acceleration by petawatt femtosecond laser solid interaction and explore strategies to enhance ion energy. The irradiation of micrometer thick (0.2–6.0 μ m ) Al foils with a virtually unexplored intensity regime (8 × 10<SUP>19</SUP> W/cm<SUP>2</SUP> – 1 × 10<SUP>21</SUP> W/cm<SUP>2</SUP>) resulting in ion acceleration along the rear and the front surface target normal direction is investigated. The maximum energy of protons and carbon ions, obtained at optimized laser intensity condition (by varying laser energy or focal spot size), exhibit a rapid intensity scaling as <SUP> I 0 . 8 </SUP> along the rear surface target normal direction and <SUP> I 0 . 6 </SUP> along the front surface target normal direction. It was found that proton energy scales much faster with laser energy rather than the laser focal spot size. Additionally, the ratio of maximum ion energy along the both directions is found to be constant for the broad range of target thickness and laser intensities.</P> <P>A proton flux is strongly dominated in the forward direction at relatively low laser intensities. Increasing the laser intensity results in the gradual increase in the backward proton flux and leads to almost equalization of ion flux in both directions in the entire energy range. These experimental findings may open new perspectives for applications.</P>
Ter-Avetisyan, S.,Andreev, A.,Platonov, K.,Sung, J. H.,Lee, S. K.,Lee, H. W.,Yoo, J. Y.,Singh, P. K.,Ahmed, H.,Scullion, C.,Kakolee, K. F.,Jeong, T. W.,Hadjisolomou, P.,Borghesi, M. The Optical Society 2016 Optics express Vol.24 No.24
<P>A significant level of back reflected laser energy was measured during the interaction of ultra-short, high contrast PW laser pulses with solid targets at 30 degrees incidence. 2D PIC simulations carried out for the experimental conditions show that at the laser-target interface a dynamic regular structure is generated during the interaction, which acts as a grating (quasi-grating) and reflects back a significant amount of incident laser energy. With increasing laser intensity above 1018 W/cm(2) the back reflected fraction increases due to the growth of the surface modulation to larger amplitudes. Above 1020 W/cm(2) this increase results in the partial destruction of the quasi-grating structure and, hence, in the saturation of the back reflection efficiency. The PIC simulation results are in good agreement with the experimental findings, and, additionally, demonstrate that in presence of a small amount of pre-plasma this regular structure will be smeared out and the back reflection reduced. (C) 2016 Optical Society of America</P>