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Wyświetlanie 1-15 z 55
Tytuł:
Health risk assessment of heavy metals in irrigation water, soil and vegetables from different farms in Riyadh district, Saudi Arabia
Autorzy:
Alturiqi, A.S.
Albedair, L.A.
Ali, M.H.H.
Powiązania:
https://bibliotekanauki.pl/articles/1192504.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
Tematy:
heavy metal
vegetables
dietary intake
health risk
HQ
THQ
ILCR
Opis:
The safety and security of different foodstuffs are considered important and have a high priority in global sustainable development. The contents of Fe, Mn, Cu, Zn, Ni, Pb and Cd were estimated in edible parts of 60 vegetable samples, irrigation water and agricultural soil collected from 5 farms in suburban areas around Riyadh district, Saudi Arabia. Also, soil pollution indices, pollution load index and contamination factor (PLI, CF), bioaccumulation factor (BAF), non-carcinogenic and carcinogenic risk indices (HQ, THQ, and ILCR) were estimated. The content of heavy metals in irrigation water and soil was within the recommended permissible levels, except for Cd in soil, which exceeds permissible levels. The trend of metal concentrations in both agricultural soil and vegetables was found in the order: Fe > Mn > Zn > Cu > Ni > Pb > Cd. Cluster analysis of the metal content in vegetables showed a tendency towards the accumulation of heavy metals in the order of leaves > roots > fruits > flowers > tuber. The BAFs values found were < 1.0, HQs values for Fe, Mn, Cu, Zn and Ni were found to be < 1, while the estimated HQs for Pb and Cd were > 1, posing greater risk to the health of adults and children. THQ values were higher for children compared to adults. ILCR values for Cd showed a serious issue, as it exceeds the threshold risk limit (>10−4) in all parts of the investigated vegetables in all sampling sites.
Źródło:
Journal of Elementology; 2020, 25, 4; 1269-1289
1644-2296
Pojawia się w:
Journal of Elementology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Exact and Explicit Solutions for Nonlinear Schrödinger Equations
Autorzy:
Aslan, İ.
Powiązania:
https://bibliotekanauki.pl/articles/1400189.pdf
Data publikacji:
2013-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.30.Jr
02.30.Hq
04.20.Jb
Opis:
Nonlinear models occur in many areas of applied physical sciences. This paper presents the first integral method to carry out the integration of Schrödinger-type equations in terms of traveling wave solutions. Through the established first integrals, exact traveling wave solutions are obtained under some parameter conditions.
Źródło:
Acta Physica Polonica A; 2013, 123, 1; 16-20
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solutions for conservative nonlinear oscillators using an approximate method based on Chebyshev series expansion of the restoring force
Autorzy:
Beléndez, A.
Hernández, A.
Beléndez, T.
Pascual, C.
Alvarez, M.
Arribas, E.
Powiązania:
https://bibliotekanauki.pl/articles/1075577.pdf
Data publikacji:
2016-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.30.Hq
02.30.Mv
05.45.-a
Opis:
Approximate solutions for small and large amplitude oscillations of conservative systems with odd nonlinearity are obtained using a "cubication" method. In this procedure, the Chebyshev polynomial expansion is used to replace the nonlinear function by a third-order polynomial equation. The original second-order differential equation, which governs the dynamics of the system, is replaced by the Duffing equation, whose exact frequency and solution are expressed in terms of the complete elliptic integral of the first kind and the Jacobi elliptic function cn, respectively. Then, the exact solution for the Duffing equation is the approximate solution for the original nonlinear differential equation. The coefficients for the linear and cubic terms of the approximate Duffing equation - obtained by "cubication" of the original second-order differential equation - depend on the initial oscillation amplitude. Six examples of different types of common conservative nonlinear oscillators are analysed to illustrate this scheme. The results obtained using the cubication method are compared with those obtained using other approximate methods such as the harmonic, linearized and rational balance methods as well as the homotopy perturbation method. Comparison of the approximate frequencies and solutions with the exact ones shows good agreement.
Źródło:
Acta Physica Polonica A; 2016, 130, 3; 667-678
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Paramagnetic Centers in DOPA-Melanin-Dihydrostreptomycin Complexes
Autorzy:
Buszman, E.
Pilawa, B.
Zdybel, M.
Wrześniok, D.
Grzegorczyk, A.
Wilczok, T.
Powiązania:
https://bibliotekanauki.pl/articles/2043624.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.Hq
76.30.Rn
Opis:
DOPA-melanin-dihydrostreptomycin complexes with drug concentrations 1×10$\text{}^{-4}$-1×10$\text{}^{-2}$ M were examined by the use of electron paramagnetic resonance spectroscopy at X-band (9.3 GHz). Dihydrostreptomycin was chosen for studies, because this aminoglycoside antibiotic causes strong toxic effects in organism. It was stated that dihydrostreptomycin generates o-semiquinone free radicals with g=2.0038 in melanin. Free radicals formation increases with increase in the antibiotic concentration. Changes of EPR lines with microwave powers pointed out that slow spin-lattice relaxation processes exist in DOPA-melanin and in its complexes with dihydrostreptomycin. The measured EPR lines were homogeneously broadened.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 353-356
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Energy Transfer and Up-Conversion in the Erbium Elpasolites Cs$\text{}_{2}$NaEr$\text{}_{x}$Y$\text{}_{1-x}$Cl$\text{}_{6}$
Autorzy:
Campbell, M.
Flint, C. D.
Powiązania:
https://bibliotekanauki.pl/articles/1945497.pdf
Data publikacji:
1996-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
13.40.Hq
31.70.Hq
34.30.+h
61.72.Ss
78.55.Hx
Opis:
The luminescence decay curves from the $\text{}^{4}$F $\text{}_{9}\text{}_{/}\text{}_{2}$ and $\text{}^{4}$I $\text{}_{9}\text{}_{/}\text{}_{2}$ states of the cubic hexachloroelpasolite crystals Cs$\text{}_{2}$NaEr$\text{}_{x}$Y$\text{}_{1-x}$Cl$\text{}_{6}$ (x = 0.001÷1) have been measured over the temperature range 10-300 K. The $\text{}^{4}$I $\text{}_{9}\text{}_{/}\text{}_{2}$ state undergoes an electric dipole vibronic-electric dipole vibronic cross-relaxation process at 300 K, but this mechanism is inefficient below 165 K. Excitation into the $\text{}^{4}$F $\text{}_{9}\text{}_{/}\text{}_{2}$ state, results in emission in the green, blue and ultra violet regions. The up-conversion processes which could account for the ultraviolet emission are discussed.
Źródło:
Acta Physica Polonica A; 1996, 90, 1; 151-160
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Response of Superconductor Bolometer to Phonon Fluxes
Autorzy:
Danilchenko, B. A.
Jasiukiewicz, Cz.
Paszkiewicz, T.
Wolski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2035733.pdf
Data publikacji:
2003-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.57.Kp
02.30.Hq
66.70.+f
Opis:
A metallic film bolometer with heat capacity C is in contact with thermal bath and with crystalline specimen and is biased by a constant current I$\text{}_{b}$. The thermal contact of the bolometer is characterized by the thermal conductance G. The bolometer operates in the linear regime of dependence of resistance on temperature characterized by a constantα. Experiments which allow one to measureα, C, and G are proposed. The characteristic timeτ=C/G and characteristic current I$\text{}_{m}=\sqrt{\text{G/α}}$ affect the effective relaxation rateΛ of the bolometer resistance R$\text{}_{b}$(t). The knowledge of the power W(t) absorbed by detector allows one to calculate R$\text{}_{b}$(t). The inverse problem of calculation of W(t) from known R$\text{}_{b}$(t) is also solved. The suitable algorithms are proposed. Deconvoluted absorbed power is obtained for experiments performed on GaAs and compared with phonoconductivity signal of two-dimensional electron gas structure as well as with results of Monte Carlo computer experiments.
Źródło:
Acta Physica Polonica A; 2003, 103, 4; 325-338
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Geometry of the Excited Charge Transfer States: Flattening or Twisting?
Autorzy:
Dobkowski, J.
Sazanovich, I.
Powiązania:
https://bibliotekanauki.pl/articles/1813988.pdf
Data publikacji:
2007-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.50.-j
61.66.Hq
Opis:
Numerous molecules built of an electron acceptor and electron donor units linked together by single bond exhibit a peculiar behavior in their low-lying electronically excited states. N,N-diethylaminoacetophenone and 4-acetyl-4'-dimethylamino-biphenyl, having acetophenone as the acceptor and differentiated by the donors groups $N(CH_3)_2$ and dimethylaniline, respectively, were selected as the subject of study. To recognize the excited state relaxation paths the stationary and time-resolved spectroscopy in absorption and emission was applied. Experimental results indicate that after excitation in polar solvents N,N-diethylaminoacetophenone reduces to minimum the overlap between π-electron systems of the donor and acceptor groups relaxing to the twisted internal charge-transfer state; contrary to that, flattening of the 4-acetyl-4'-dimethylamino-biphenyl skeleton generates increase in the overlap of the π-electron systems.
Źródło:
Acta Physica Polonica A; 2007, 112, S; S-127-S-142
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stabilized 1D Metal in TTF(Ni(dmit)$\text{}_{2}$)$\text{}_{2}$ through Very Weak Coupling between Phonons and Weakly Correlated Fermions
Autorzy:
Doublet, M. L.
Malfant, I.
Hebrard, S.
Canadell, E.
Gaultier, J.
Chasseau, D.
Legros, J. P.
Brossard, L.
Powiązania:
https://bibliotekanauki.pl/articles/1933351.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Hk
71.45.Lr
61.66.Hq
Opis:
Extended Hückel band structure calculations derived from low temperature X-ray structural data, provide evidence, as temperature decreases, for an increasing 1D character of the multiparallel bands of the TTF(Ni(dmit)$\text{}_{2}$)$\text{}_{2}$ compound. This result is discussed within the monotonous metallic behaviour of the weakly correlated fermions gas, despite condensations of charge density wave instabilities.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 781-784
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Casimir Force between Nanoparticles Immersed in a Crosslinked Polymer Blend
Autorzy:
El Fassi, S.
Benhamou, M.
Boughou, M.
Kaidi, H.
El Yaznasni, M.
Ridouane, H.
Powiązania:
https://bibliotekanauki.pl/articles/1535673.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.25.Hq
64.75.+g
82.70.Gg
Opis:
We consider a crosslinked polymer blend made of two polymers of different chemical nature. We suppose that such a system incorporates small colloidal particles, which prefer to be attracted by one polymer, close to the spinodal temperature. This is the so-called critical adsorption. As assumption, the particle diameter, $d_0$, is considered to be small enough in comparison with the size of microdomains (mesh size) ξ* ~ $an^{1//2}$, with a - the monomer size and n - the number of monomers between consecutive crosslinks. The critical fluctuations of the crosslinked polymer mixture induce a pair-potential between particles located in the non-preferred phase. The purpose is the determination of the Casimir pair-potential, $U_2 (r)$, as a function of the interparticle distance r. To achieve calculations, use is made of an extended de Gennes field theory that takes into account the colloid-polymer interactions. Within the framework of this theory, we first show that the pair-particle is attractive. Second, we find for this potential the exact form: $U_2(r)//k_{B}T = - A_{H}(d_0//r)^2 exp(-r//ξ*) - B_{H}(d_0//r)^4 exp(-2r//ξ*)$, with the known universal amplitudes $A_{H}$ > 0 and $B_{H}$ > 0 (the Hamaker constants). This expression clearly shows that the pair-potential differs from its homologue with no crosslinks only by the two exponential factors exp(-r/ξ*) and exp(-2r/ξ*). The main conclusion is that the presence of reticulations reduces substantially the Casimir effect in crosslinked polymer blends.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 606-612
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analytic Approximations for Thomas-Fermi Equation
Autorzy:
El-Nahhas, A.
Powiązania:
https://bibliotekanauki.pl/articles/1812056.pdf
Data publikacji:
2008-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.30.Hq
02.30.Mv
02.60.Lj
21.10.Ft
31.15.-p
Opis:
In this paper, we give an analytic approximation to the solution of the Thomas-Fermi equation using the homotopy analysis method and with the use of a polynomial exponential basis.
Źródło:
Acta Physica Polonica A; 2008, 114, 4; 913-918
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solution of a Class of Optimization Problems Based on Hyperbolic Penalty Dynamic Framework
Autorzy:
Evirgen, F.
Powiązania:
https://bibliotekanauki.pl/articles/1031640.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.60.Pn
02.70.-c
02.30.Hq
Opis:
In this study, a gradient-based dynamic system is constructed in order to solve a certain class of optimization problems. For this purpose, the hyperbolic penalty function is used. Firstly, the constrained optimization problem is replaced with an equivalent unconstrained optimization problem via the hyperbolic penalty function. Thereafter, the nonlinear dynamic model is defined by using the derivative of the unconstrained optimization problem with respect to decision variables. To solve the resulting differential system, a steepest descent search technique is used. Finally, some numerical examples are presented for illustrating the performance of the nonlinear hyperbolic penalty dynamic system.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 1062-1065
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Explicit Analytic Solution to the Thomas-Fermi Equation by the Improved Differential Transform Method
Autorzy:
Fatoorehchi, H.
Abolghasemi, H.
Powiązania:
https://bibliotekanauki.pl/articles/1198516.pdf
Data publikacji:
2014-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.30.Hq
02.30.Mv
02.60.Lj
21.10.Ft
31.15.-p
Opis:
In this paper, a newly proposed analytical scheme by the authors namely the improved differential transform method is employed to provide an explicit series solution to the Thomas-Fermi equation. The solution procedure is very straightforward, requiring merely elementary operations together with differentiation, and ends up in a recursive formula involving the Adomian polynomials to afford the unknown coefficients. Unlike many other methods, our approach is free of integration and hence can be of computational interest. In addition, a very good agreement between the proposed solution and the results from several well-known works in the literature is demonstrated.
Źródło:
Acta Physica Polonica A; 2014, 125, 5; 1083-1087
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Case Study of Diffusion of Innovation under Competition
Autorzy:
Gündüç, S.
Powiązania:
https://bibliotekanauki.pl/articles/1029620.pdf
Data publikacji:
2018-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
PACS/topics:02.30.Hq
02.60.Cb
89.65.Gh
Opis:
In this work, the aim is to discuss the relative importance of the driving parameters of the diffusion of innovation under competition. As a case study the competitive existence of Android and iOS operating systems are modeled in the context of an extended Bass model. The chosen model consists of two coupled differential equations. Each differential equation has the same form of the well known Bass equation with an extra term which represents the effect of the existence of the competitor. Since the smartphone sales and usage are globally well documented, publicly available global smartphone market share and sales data are used to determine the model parameter values. The smartphone global market share data spans 28 quarters starting from the first quarter of 2009. The distribution of the market share in the first quarter has been used as the initial values of the competing operating systems. A minimization process obtains the free parameters (six in total) of the differential equations. The values of the parameters are fixed by minimizing the difference between the solution of Bass equation and the smartphone global market share data. The parameter values of iOS and Android operating systems indicate that, on the worldwide scale, the adaptation of new ideas/products the dominantly led by the personal interactions. In fact, through social networks, information flow is immense, and individuals rely on the information obtained directly from a trusted individual. Publicity parameter values indicate that very rarely decision of an individual is formed by only the mass media or publicity. On the contrary, to the publicity parameter, it is observed that the existence of a competitor has a considerable effect on the sales of both parties.
Źródło:
Acta Physica Polonica A; 2018, 133, 6; 1465-1469
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Laguerre polynomial solutions of a class of initial and boundary value problems arising in science and engineering fields
Autorzy:
Gürbüz, B.
Sezer, M.
Powiązania:
https://bibliotekanauki.pl/articles/1061583.pdf
Data publikacji:
2016-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.30.Gp
02.30.Hq
02.70
Opis:
In this study, we consider high-order nonlinear ordinary differential equations with the initial and boundary conditions. These kinds of differential equations are essential tools for modelling problems in physics, biology, neurology, engineering, ecology, economy, astrophysics, physiology and so forth. Each of the mentioned problems are described by one of the following equations with the specific physical conditions: Riccati, Duffing, Emden-Fowler, Lane Emden type equations. We seek the approximate solution of these special differential equations by means of a operational matrix technique, called the Laguerre collocation method. The proposed method is based on the Laguerre series expansion and the collocation points. By using the method, the mentioned special differential equations together with conditions are transformed into a matrix form which corresponds to a system of nonlinear algebraic equations with unknown Laguerre coefficients, and thereby the problem is approximately solved in terms of Laguerre polynomials. In addition, some numerical examples are presented to demonstrate the efficiency of the proposed method and the obtained results are compared with the existing results in literature.
Źródło:
Acta Physica Polonica A; 2016, 130, 1; 194-197
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 55

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