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1.
Sci Rep ; 11(1): 16291, 2021 Aug 11.
Artículo en Inglés | MEDLINE | ID: mdl-34381101

RESUMEN

Hydrochemical and isotopic characteristics of fluids from major geothermal fields of middle/low temperature in N/NE Greece are examined [basins: Strymon River (SR), Nestos River Delta (ND), Xanthi-Komotini (XK), Loutros-Feres-Soufli (LFS) and Rhodope Massif]. The geodynamic context is reflected to isotopic/chemical composition of fluids, heat flow values and elevated CO2 concentrations in emitted fluids. B and Li are derived from leaching of the geothermal systems hosting rocks. δ18OH2O, δ18OSO4, δ13CCO2 values and chemical compositions of Cl, B and Li of geothermal discharges suggest two distinct source fluids. Fluids in SR exhibit high B/Cl and Li/Cl ratios, suggesting these constituents are derived from associated magmas of intermediate composition (andesitic rocks). Geothermal discharges in LFS exhibit low B/Cl and Li/Cl ratios, implying acid (rhyolitic) magmatism. δ13CCO2 and CO2/(CO2 + 105He) ratios in the west part, suggest fluids affected by addition of volatiles released from subducted marine sediments. For the eastern systems, these ratios suggest gas encountered in systems issued from mixing of crustal and mantle-derived volatiles. Isotopic geothermometers reflect, for the same direction, equilibrium processes more (LFS, XK) or less (SR) pronounced and discriminate the geothermal field from low to middle [SR, ND (Erasmio)] and middle to high enthalpy [ND (Eratino), LFS, XK].

3.
J Phys Condens Matter ; 28(49): 495101, 2016 12 14.
Artículo en Inglés | MEDLINE | ID: mdl-27731310

RESUMEN

We call monomer a B-DNA base pair and study, analytically and numerically, electron or hole oscillations in monomers, dimers and trimers. We employ two tight binding (TB) approaches: (I) at the base-pair level, using the on-site energies of the base pairs and the hopping parameters between successive base pairs i.e. a wire model, and (II) at the single-base level, using the on-site energies of the bases and the hopping parameters between neighbouring bases, specifically between (a) two successive bases in the same strand, (b) complementary bases that define a base pair, and (c) diagonally located bases of successive base pairs, i.e. an extended ladder model since it also includes the diagonal hoppings (c). For monomers, with TB II, we predict periodic carrier oscillations with frequency [Formula: see text]-550 THz. For dimers, with TB I, we predict periodic carrier oscillations with [Formula: see text]-100 THz. For trimers made of identical monomers, with TB I, we predict periodic carrier oscillations with [Formula: see text]-33 THz. In other cases, either with TB I or TB II, the oscillations may be not strictly periodic, but Fourier analysis shows similar frequency content. For dimers and trimers, TB I and TB II are successfully compared giving complementary aspects of the oscillations.


Asunto(s)
ADN/química , Emparejamiento Base , Electrones , Sustancias Macromoleculares , Polímeros/química
4.
Phys Rev E ; 94(6-1): 062403, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28085358

RESUMEN

We employ two tight-binding (TB) approaches to systematically study the electronic structure and hole or electron transfer in B-DNA monomer polymers and dimer polymers made up of N monomers (base pairs): (I) at the base-pair level, using the onsite energies of base pairs and the hopping integrals between successive base pairs, i.e., a wire model and (II) at the single-base level, using the onsite energies of the bases and the hopping integrals between neighboring bases, i.e., an extended ladder model since we also include diagonal hoppings. We solve a system of M (matrix dimension) coupled equations [(I) M=N, (II) M=2N] for the time-independent problem, and a system of M coupled first order differential equations for the time-dependent problem. We perform a comparative study of stationary and time-dependent aspects of the two TB variants, using realistic sets of parameters. The studied properties include HOMO and LUMO eigenspectra, occupation probabilities, density of states and HOMO-LUMO gaps as well as mean over time probabilities to find the carrier at each site [(I) base pair or (II) base], Fourier spectra, which reflect the frequency content of charge transfer, and pure mean transfer rates from a certain site to another. The two TB approaches give coherent, complementary aspects of electronic properties and charge transfer in B-DNA monomer polymers and dimer polymers.


Asunto(s)
ADN Forma B/química , Fenómenos Electrofisiológicos , Modelos Biológicos , Polímeros/química , Emparejamiento Base , Análisis Espectral
5.
J Chem Phys ; 140(16): 164102, 2014 Apr 28.
Artículo en Inglés | MEDLINE | ID: mdl-24784248

RESUMEN

Photoinduced charge-transfer processes play a key role for novel photovoltaic phenomena and devices. Thus, the development of ab initio methods that allow for an accurate and computationally inexpensive treatment of charge-transfer excitations is a topic that nowadays attracts a lot of scientific attention. In this paper we extend an approach recently introduced for the description of single and double excitations [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013); M. Tassi, I. Theophilou, and S. Thanos, J. Chem. Phys. 138, 124107 (2013)] to allow for the description of intermolecular charge-transfer excitations. We describe an excitation where an electron is transferred from a donor system to an acceptor one, keeping the excited state orthogonal to the ground state and avoiding variational collapse. These conditions are achieved by decomposing the space spanned by the Hartree-Fock (HF) ground state orbitals into four subspaces: The subspace spanned by the occupied orbitals that are localized in the region of the donor molecule, the corresponding for the acceptor ones and two more subspaces containing the virtual orbitals that are localized in the neighborhood of the donor and the acceptor, respectively. Next, we create a Slater determinant with a hole in the subspace of occupied orbitals of the donor and a particle in the virtual subspace of the acceptor. Subsequently we optimize both the hole and the particle by minimizing the HF energy functional in the corresponding subspaces. Finally, we test our approach by calculating the lowest charge-transfer excitation energies for a set of tetracyanoethylene-hydrocarbon complexes that have been used earlier as a test set for such kind of excitations.

6.
Int J Sports Med ; 35(8): 639-44, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24424961

RESUMEN

We investigated the renal effects of a high-intensity exercise (HIE) program based on strength training. 20 Wistar rats were randomly assigned to 2 experimental groups performing HIE or control over 12 weeks. Urinary volume, pH, citrate and calcium, and plasma urea, total proteins, creatinine, albumin, lactate dehydrogenase, creatine kinase (CK), calcium, magnesium, corticosterone and testosterone were measured. We also studied renal morphology with the Fibrosis HR(®) software. Plasma urea and CK concentrations were higher in the HIE compared to the control group (p < 0.05), whereas plasma creatinine was lower (p < 0.01). Plasma corticosterone was higher (p < 0.05) and testosterone lower (p < 0.01) in the HIE group. Except for the higher urinary volume found in the HIE group (p < 0.05), no differences between groups were observed in the rest of urinary parameters analyzed. Renal interstitial connective tissue was ~30% higher in the HIE group (p < 0.05). Glomerular tufts and mesangial areas were also higher in the HIE group (all, p < 0.05). No differences between groups were observed in the glomerular area. Overall, HIE promoted a worse morphological renal profile that might be associated with a higher risk for incidence of kidney disease in the long-term. The stress induced by the type of exercise performed could be on the basis of this worse morphological renal status.


Asunto(s)
Riñón/anatomía & histología , Riñón/metabolismo , Condicionamiento Físico Animal , Entrenamiento de Fuerza , Animales , Biomarcadores/sangre , Biomarcadores/orina , Peso Corporal , Corticosterona/sangre , Creatina Quinasa/orina , Ingestión de Alimentos , Masculino , Músculo Esquelético/metabolismo , Nitrógeno/metabolismo , Tamaño de los Órganos , Distribución Aleatoria , Ratas Wistar , Estrés Fisiológico , Testosterona/sangre , Urea/sangre
7.
J Chem Phys ; 138(12): 124107, 2013 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-23556709

RESUMEN

Doubly excited states have nowadays become important in technological applications, e.g., in increasing the efficiency of solar cells and therefore, their description using ab initio methods is a great theoretical challenge as double excitations cannot be described by linear response theories based on a single Slater determinant. In the present work we extend our recently developed Hartree-Fock (HF) approximation for calculating singly excited states [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013)] in order to allow for the calculation of doubly excited states. We describe the double excitation as two holes in the subspace spanned from the occupied HF orbitals and two particles in the subspace of virtual HF orbitals. A subsequent minimization of the energy results to the determination of the spin orbitals of both the holes and the particles in the occupied and virtual subspaces, respectively. We test our method, for various atoms, H2 and polyene molecules which are known to have excitations presenting a significant double excitation character. Importantly, our approach is computationally inexpensive.


Asunto(s)
Teoría Cuántica , Electrones , Hidrógeno/química , Polienos/química
8.
Eur Child Adolesc Psychiatry ; 8(3): 165-72, 1999 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-10550697

RESUMEN

Achenbach's Child Behavior Checklist (CBCL) and Teachers' Report Form (TRF) were administered to 6-12 year old school children comprising a large random community sample (n = 1200) drawn from the whole of Greece. These are the first data on the TRF in Greece and the first nation-wide data on the CBCL. Appropriate cutoff points for the behavioral problems and competence scales of both questionnaires were obtained for boys and girls. These were considerably higher than USA cutoffs for the CBCL but not for the TRF. Analysis of scores in relation to degree of urbanization showed that it was not necessary to define different cutoffs in different strata. Parents' and teachers' ratings of the same child were most highly correlated for Externalizing and Aggressive behavior for boys and for Attention problems for both sexes.


Asunto(s)
Trastornos de la Conducta Infantil/diagnóstico , Escalas de Valoración Psiquiátrica/normas , Niño , Femenino , Grecia , Humanos , Masculino , Relaciones Padres-Hijo , Valores de Referencia , Instituciones Académicas , Sensibilidad y Especificidad , Población Urbana
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