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Wyświetlanie 1-15 z 16
Tytuł:
Geopolymerisation of Mechanically Activated Lignite and Brown Coal Fly Ash
Autorzy:
Mucsi, G.
Molnár, Z.
Kumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/1375557.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Wk
Opis:
Geopolymers have been synthesized from mechanically activated lignite and brown coal fly ash. Mechanical activation of fly ash has been carried out using laboratory ball mill. To determine the structural changes in both, the fly ash and the resulted geopolymer, Fourier transform infrared spectroscopy measurements were performed. Isothermal conduction calorimetry method was applied to study the geopolymerisation reactions in mechanically non-activated (raw) and activated fly ash samples. The isothermal conduction calorimetry results showed similar peak intensity for mechanically activated (5-30 min) fly ash samples. However, the intensity of peak for 120 min milled brown coal fly ash was the highest. The compressive strength of the specimen was found to be dependent on the grinding residence time as well as composition/type of fly ash.
Źródło:
Acta Physica Polonica A; 2014, 126, 4; 994-998
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis of $Fe_4[Fe(CN)_6]_3$·$14H_2O$ Nanopowder by Co-Precipitation Technique and Effect of Heat Treatment
Autorzy:
Rohilla, S.
Lal, B.
Sunder, S.
Aghamkar, P.
Kumar, S.
Aggarwal, A.
Powiązania:
https://bibliotekanauki.pl/articles/1535871.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
64.70.Nd
61.82.Rx
Opis:
Nanopowder of iron cyanide hydrate (member of Prussian blue family) was obtained using ferric chloride and potassium cyanide in their dilute solution through co-precipitation method. The effect of thermal annealing on iron cyanide hydrate nanocrystallites have been studied in detail. The formation of $Fe_4[Fe(CN)_6]_3$·$14H_2O$ and iron oxides was revealed by the Fourier transform infrared spectroscopy. The crystal structure, morphology and size of nanocrystallites were investigated by X-ray diffraction and transmission electron microscope. Results suggest that using co-precipitation technique, nanopowder of iron cyanide hydrate, in typically spherical shape, can be obtained and their thermal treatment also yield iron oxide nanocrystallites of spherical with good homogeneity. The size of the prepared nanocrystallites was found in the range 20-36 nm. It was observed that thermal treatment, typically at 800°C (4 h), iron cyanide hydrate ($Fe_4[Fe(CN)_6]_3$·$14H_2O$) nanocrystallites transformed into iron oxide ($α-Fe_2O_{3,}$ hematite) nanocrystallites.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 696-700
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Spin-Valve Transistor - a New Magnetoelectronic Device
Autorzy:
Anil Kumar, P. S.
Lodder, J. C.
Powiązania:
https://bibliotekanauki.pl/articles/2011222.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.70.-i
75.70.Pa
Opis:
A spin-valve transistor showing high sensitivity at low fields was developed. A large magnetocurrent, above 500% is realized by a magnetic field change of 2 to 4 Oe at 80 K. Hot electrons are injected into the spin-valve layer through a Si-Pt Schottky diode. These hot electrons, while traversing through the spin-valve, are spin-dependently scattered. Those electrons with right energy and momentum are collected by a collector (an Au-Si Schottky diode) constituting a collector current. The relative orientation of the magnetic layer in the spin-valve is changed by the application of a magnetic field and causes a change in collector current giving a large magnetocurrent.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 111-118
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Embedded Solitons and Conservation Law with $χ^{(2)}$ and $χ^{(3)}$ Nonlinear Susceptibilities
Autorzy:
Savescu, M.
Kara, A.
Kumar, S.
Krishnan, E.
Zaka Ullah, M.
Moshokoa, S.
Zhou, Qin
Biswas, A.
Powiązania:
https://bibliotekanauki.pl/articles/1398312.pdf
Data publikacji:
2017-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
solitons
χ^{(2)}
conservation laws
Opis:
This paper studies embedded solitons that are confined to continuous spectrum, with $χ^{(2)}$ and $χ^{(3)}$ nonlinear susceptibilities. Bright and singular soliton solutions are obtained by the method of undetermined coefficients. Subsequently, the Lie symmetry analysis and mapping method retrieves additional solutions to the model such as shock waves, singular solitons, cnoidal waves, and several others. Finally, a conservation law for this model is secured through the Lie symmetry analysis.
Źródło:
Acta Physica Polonica A; 2017, 131, 2; 297-303
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Quantitative Approach for the Determination of Light Induced Defects in $a-Se_{90}Sb_{10-x}Ag_x$ Thin Films by Using Thermally Stimulated Current Technique
Autorzy:
Kumar, Anjani
Tripathi, S.
Kumar, A.
Powiązania:
https://bibliotekanauki.pl/articles/1398969.pdf
Data publikacji:
2016-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Jv
72.80.Ng
Opis:
Thin films of $Se_{90}Sb_{10-x}Ag_x$ (x=0, 2, 4, 6, 8) glasses have been prepared by vacuum evaporation technique. Present study reports the quantitative estimation of light induced defects in aforesaid thin films by using thermally stimulated current technique. Measurements have been made in a vacuum ≈10¯³ Torr before and after exposing amorphous films to white light for different exposure times (0 to 6 h). Results indicate that light induced defects are created due to prolonged exposure of light and this is explained by a microscopic model proposed by Shimakawa and co-workers. It is also found that fractional increase in light induced defect density decreases as Ag concentration increases. A discontinuity has, however, been observed at 4 at.% of Ag which is explained in terms of average coordination number.
Źródło:
Acta Physica Polonica A; 2016, 129, 6; 1178-1183
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oscillator Strengths of the 1s2s$\text{}^{1}$S$\text{}^{e}$ → 1s2p$\text{}^{1}$P$\text{}^{0}$ Transition in He
Autorzy:
Tiwary, S. N.
Kumar, P.
Powiązania:
https://bibliotekanauki.pl/articles/1887915.pdf
Data publikacji:
1991-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.10.+z
Opis:
The paper presents configuration interaction (CI) calculations of both the length and velocity forms of the oscillator strengths for 1s2s$\text{}^{1}$S$\text{}^{e}$ → 1s2p$\text{}^{1}$P$\text{}^{0}$ transition in the He atom. For the first time the agreement between the length and velocity values to within about 0.045% has been achieved.
Źródło:
Acta Physica Polonica A; 1991, 80, 1; 23-28
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Core-Shell Mechanocomposites of Drugs with Inorganic Oxides and Hydroxides
Autorzy:
Shakhtshneider, T.
Myz, S.
Boldyreva, E.
Nizovskii, A.
Kumar, Rakesh
Powiązania:
https://bibliotekanauki.pl/articles/1375599.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.25.-g
Opis:
The composites of piroxicam and meloxicam with gamma-alumina, aluminium hydroxides (gibbsite and boehmite), alpha and gamma polymorphs of iron(III) oxide having different surface area and morphology were prepared by planetary ball-milling. It has been shown that the initial state of the excipient (specific surface area, particle size and morphology) had a pronounced effect on the formation of the core-shell composites with the drugs and their properties. The X-ray diffraction patterns and IR spectra measured for co-milled samples as well as X-ray photoelectron spectroscopy studies gave evidence that the components of the mixtures interacted with each other and became amorphous, as composites were formed. The drug release from the composites was different as compared with pure drugs, meloxicam and piroxicam behaving differently that can be explained by formation of strong or weak bonds with the active sites of the carriers. In the case of mechanocomposites, the drugs dissolved quickly due to high surface of organic phase in the core-shell composites. The high-porous carriers can serve as the sorbents for the drugs in solution.
Źródło:
Acta Physica Polonica A; 2014, 126, 4; 1019-1024
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Collision cascade and spike effects of X-ray irradiation on optoelectronic devices
Autorzy:
Salleh, S.
Abdul Amir, H.
Kumar Tiwari, A.
Pien Chee, F.
Powiązania:
https://bibliotekanauki.pl/articles/1065735.pdf
Data publikacji:
2016-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
24.10.-i
25.45.De
25.45.Hi
32.80.-t
32.80.Fb
Opis:
Bombardment with high energy particles and photons can cause potential hazards to the electronic systems. These effects range from degradation of performance to functional failure, which can affect the operation of a system. Such failures become increasingly likely as electronic components are getting more sophisticated, while decreasing in size and tending to a larger integration. In this paper, the effects of X-ray irradiation on a plastic encapsulated infrared light emitting diode, coupled to a plastic encapsulated silicon infrared phototransistor, with both of them being electrically isolated at ON and OFF modes, are investigated. All the devices are exposed to a total dose of up to 1000 mAs. The electrical parameters of the optoelectronic devices during the radiation exposure and at post-irradiation are compared to the pre-irradiation readings. The findings show that the highest degradation occurs at low dose of exposure; beyond 100 mAs the relative decrease in collector current of the phototransistor is gradually reduced. The most remarkable feature found, is the operational dependence of the bias collector current, indicating a higher degradation for low bias forward current of the light emitting diode. The degradation induced at the forward current of the light emitting diode by X-rays irradiation is almost negligible whereas a decrease of the rate of change in current transfer ratio is significant during the X-ray irradiation. The results show that there is no significant difference between current transfer ratio of ON mode and OFF mode radiation. It is observed that the operating mode of the optoelectronic devices after exposure to 1000 mAs of X-ray irradiation contributes no major variation in the degree of damage.
Źródło:
Acta Physica Polonica A; 2016, 130, 1; 93-97
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Point Spread Function of Asymmetrically Apodized Optical Systems with Complex Pupil Filters: The One-Dimensional Case with Slit Aperture
Autorzy:
Keshavulu Goud, M.
Komala, R.
Naresh Kumar Reddy, A.
Goud, S.
Powiązania:
https://bibliotekanauki.pl/articles/1419735.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.25.Fx
42.30.Kq
42.79.Ci
Opis:
Aimed at high resolution, an asymmetric point spread function has been obtained with good and bad sides by introducing three level asymmetric pupil functions. The good side has decreased side lobes while the bad side has increased side lobes. The asymmetry has been found to increase with the width of the edge strips within the slit aperture. On the other hand, there does not appear dependence of the asymmetry of the point spread function on the degree of amplitude apodization. But the magnitude of reduction of optical side-lobes is found to increase to a great extent by the amplitude apodization.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 90-95
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Eight-Channel Optical Add Drop Multiplexer Based on Ring Resonator Using LNOI Channel Waveguides
Autorzy:
Kumar, H.
Janyani, V.
Buryy, O.
Ubizskii, S.
Sugak, D.
Singh, G.
Powiązania:
https://bibliotekanauki.pl/articles/1030850.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.79.Sz
Opis:
In this paper we report on an eight-channel optical add drop multiplexer based on ring resonator using lithium niobate on insulator channel waveguides. It is suitable for a DWDM-GPON network with channel spacing of 100 GHz in C-band and data rate is 10 Gbps. The insertion loss at the drop port is maximum 1.2 dB and the Q-factor is 1636. It can be used as multiplexer as well as demultiplexer in 8-channel DWDM systems.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 997-999
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
DFT and TD-DFT Calculations of Some Metal Free Phthalonitrile Derivatives for Enhancement of the Dye Sensitized Solar Cells
Autorzy:
Anbarasan, P.
Senthil Kumar, P.
Vasudevan, K.
Moorthy Babu, S.
Aroulmoji, V.
Powiązania:
https://bibliotekanauki.pl/articles/1505357.pdf
Data publikacji:
2011-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Qn
31.10.+z
71.15.Mb
32.30.-r
Opis:
The geometries, electronic structures, polarizabilities, and hyperpolarizabilities of organic dye sensitizers 3,4-pyridinedicarbonitrile, 3-aminophthalonitrile, 4-aminophthalonitrile and 4-methylphthalonitrile were studied based on density functional theory using the hybrid functional B3LYP. Ultraviolet-visible spectra were investigated by time dependent density functional theory. The features of electronic absorption spectra in the visible and near-UV regions were assigned based on time dependent density functional theory calculations. The absorption bands are assigned to π → π* transitions. Calculated results suggest that the three lowest energy excited states of 3,4-pyridinedicarbonitrile, 3-aminophthalonitrile, 4-aminophthalonitrile and 4-methylphthalonitrile are due to photoinduced electron transfer processes. The interfacial electron transfer between semiconductor $TiO_2$ electrode and dye sensitizers 3,4-pyridinedicarbonitrile, 3-aminophthalonitrile, 4-aminophthalonitrile and 4-methylphthalonitrile is due to an electron injection process from excited dyes to the semiconductor's conduction band. The role of amide and methyl groups in phthalonitrile in geometries, electronic structures, and spectral properties were analyzed in a comparative study of 3,4-pyridinedicarbonitrile, 3-aminophthalonitrile, 4-aminophthalonitrile and 4-methylphthalonitrile for the improvement of dye sensitized solar cells.
Źródło:
Acta Physica Polonica A; 2011, 119, 3; 395-404
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vibrational Spectroscopy of H_2O by Lie Algebraic Methods
Autorzy:
Karumuri, S.
Srinivas, G.
Sunil Babu, K.
Sundara Siva Kumar, V.
Hanumaiah, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399490.pdf
Data publikacji:
2013-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.65.Fd
02.20.Sv
33.20.Ea
Opis:
An algebraic model of coupled anharmonic oscillators is introduced, capable of describing the stretching vibrations of medium-size molecules. This model is applied to the calculation of O-H vibrational modes of water molecules. In this paper, we have reported the stretching and bending vibrational energy levels of water molecule using the algebraic and density functional theory method. The results obtained by theoretical models show good agreement with the experimental values.
Źródło:
Acta Physica Polonica A; 2013, 124, 1; 3-5
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Elastic Properties of Double-Layered Manganite $La_{1.2}Sr_{1.8-x}Ba_xMn_2O_7$ (x=0.0-0.4)
Autorzy:
Reddy, Y.
Prashanth Kumar, V.
Ramesh, S.
Venkanna, S.
Ramana Reddy, M.
Kistaiah, P.
Vishnuvardhan Reddy, C.
Powiązania:
https://bibliotekanauki.pl/articles/1812358.pdf
Data publikacji:
2008-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Gk
75.47.Lx
Opis:
The elastic behavior of the sol-gel prepared double-layered manganite system $La_{1.2}Sr_{1.8-x}Ba_xMn_2O_7$ (x = 0.0-0.4) was investigated at 300 K, employing ultrasonic pulse transmission technique at 1 MHz. The values of elastic moduli and acoustic Debye temperature $(θ_D)$ were computed from longitudinal and shear velocities. The measured values were corrected to zero porosity using Hasselman and Fulrath's formula. The elastic constants of the samples, estimated using Modi's heterogeneous metal-mixture rule, were also reported. The variation of elastic moduli with Ba concentration was interpreted in terms of strength of interatomic bonding.
Źródło:
Acta Physica Polonica A; 2008, 113, 6; 1687-1694
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Optical Behaviour οf~Ni Doped CdS Nanoparticles Synthesized by Chemical Co-Precipitation Method
Autorzy:
Siva Kumar, K.
Divya, A.
Sreedhara Reddy, P.
Uthanna, S.
Martins, R.
Elangovan, E.
Powiązania:
https://bibliotekanauki.pl/articles/1492639.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.Cp
61.72.-y
78.55.Et
78.67.Bf
Opis:
Pure and Ni (2 at.%) doped cadmium sulfide (CdS) nanoparticles have been synthesized by chemical co-precipitation method at room temperature. Effect of Ni doping on CdS compound semiconductors has been analyzed using X-ray diffractometer, transmission electron microscope, energy dispersive spectroscopy, Raman and optical absorption studies. X-ray diffraction study confirmed the structure of the obtained nanoparticles to be single-phase zinc blende with the diffractions from (111), (220) and (311) planes. Energy dispersive spectroscopy study confirmed the presence of Ni in the CdS lattice. The average particle size obtained from the transmission electron microscopy studies are in agreement with the crystallite size calculated from X-ray diffraction data. The optical studies exhibited a clear red shift of absorption edge as a function of Ni doping.
Źródło:
Acta Physica Polonica A; 2011, 120, 6A; A-052-A-054
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanochemical Preparation of Organic-Inorganic Hybrid Materials of Drugs with Inorganic Oxides
Autorzy:
Shakhtshneider, T.
Myz, S.
Dyakonova, M.
Boldyrev, V.
Boldyreva, E.
Nizovskii, A.
Kalinkin, A.
Kumar, Rakesh
Powiązania:
https://bibliotekanauki.pl/articles/1503409.pdf
Data publikacji:
2011-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.25.-g
Opis:
The nanocomposites of piroxicam and meloxicam with alumina were obtained by ball-milling as a result of distribution of the drugs at the surface of oxide with formation of the stable composites. The observed changes in the IR spectra of the ball-milled mixtures suggested the interaction of the drugs with the alumina active surface sites. The functional groups in molecules of piroxicam and meloxicam involved into formation of bonds between the drugs and the surface of the oxide were determined, they are amide, sulfate, enol groups, and pyridyl / thiazolyl nitrogen atoms. It appears that the formation of the new bonds at the contacts of particles in the composite leads to the stabilization of the drugs in metastable state inhibiting their transformation into initial crystalline form.
Źródło:
Acta Physica Polonica A; 2011, 120, 2; 272-278
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 16

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