The dependence of critical temperature on oxygen concentration in YBa2Cu3O6+x in terms of the fragmented chain model

An extended ASYNNNI model, that beside nearest-neighbour and next-nearest neighbour O-O interactions in the basal plane also includes interactions between the three nearest oxygen atoms, is used to describe the statistics of CuO chain fragmentation and to calculate doping and T (c) in YBa2Cu3O6+x . Calculations were made by the Monte Carlo method employing the recently proposed charge transfer model that assumes only chains whose length is equal to, or exceeds, a characteristic (critical) length, l (cr) , can provide holes to the layers and contribute to doping p. The obtained p(x) is then combined with a universal T (c) versus p relation to yield T (c) (x) characteristics that correlate remarkably with those reported in recent experiments. The best coordination between theoretical and experimental T (c) (x) characteristics has been achieved for l (cr) = 2, implying that only isolated basal plane oxygen atoms (trivial chains) do not contribute holes to CuO2 layers

Supplementary data for article: Krstić, N. M.; Pavlović, V. D.; Novaković, I. T.; Matić, I. Z.; Sladić, D. Synthesis, Characterization and Biological Evaluation of Some Novel P-Heterocyclic Androst-4-Ene Derivatives. Molecular Diversity 2013, 17 (3), 547–561. https://doi.org/10.1007/s11030-013-9455-9

Supplementary material for: [https://doi.org/10.1007/s11030-013-9455-9]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1376

Supplementary data for article: Krstić, N. M.; Pavlović, V. D.; Novaković, I. T.; Matić, I. Z.; Sladić, D. Synthesis, Characterization and Biological Evaluation of Some Novel P-Heterocyclic Androst-4-Ene Derivatives. Molecular Diversity 2013, 17 (3), 547–561. https://doi.org/10.1007/s11030-013-9455-9

Supplementary material for: [https://doi.org/10.1007/s11030-013-9455-9]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1376

Prirodno prečišćavanje podzemnih voda zagađenih naftnim ugljovodonicima - mehanizam, koncepcija istraživanja, primena u praksi

Natural attenuation includes a number of processes that cause the reduction of groundwater contamination by petroleum hydrocarbons. Among these processes biodegradation often plays a major role, since microorganisms use petroleum hydrocarbons as the source of energy and carbon. Application of natural attenuation as a remediation approach requires detailed hydrogeological characterization of the contaminated site and monitoring of attenuation processes. This paper presents the results of monitored natural attenuation at the site of historical contamination by kerosene near Kraljevo. In order to demonstrate effects of biodegradation, following parameters in groundwater were measured: total petroleum hydrocarbons (TPH), electron acceptors (O2, NO3, SO4 2-), metabolic products of biodegradation (Mn, Fe), and redox potential (Eh). Obtained results and methodological approach can be considered useful in conceptualizing future studies of this type.Prirodno prečišćavanje objedinjuje niz procesa koji dovode do smanjenja zagađenja podzemnih voda naftnim ugljovodonicima. Biodegradacija često ima glavnu ulogu među ovim procesima, pošto mikroorgranizmi koriste naftne ugljovodonike kao izvor energije i ugljenika. Primena prirodnog prečišćavanja kao remedijacionog tretmana podrazumeva detaljnu hidrogeološku karakterizaciju zagađene lokacije i osmatranje procesa kojim dolazi do smanjenja zagađenja. U radu su prikazani rezultati osmatranja prirodnog prečišćavanja na lokaciji istorijskog zagađenja kerozinom kod Kraljeva. U cilju osmatranja efekata biodegradacije, u podzemnim vodama su vršena merenja sledećih parametara: ukupnih naftnih ugljovodonika (TPH), elektron akceptora (O2, NO3 -, SO4 2-), metaboličkih produkata biodegradacije (Mn, Fe) i redoks potencijala (Eh). Dobijeni rezultati i metodološki pristup mogu se smatrati korisnim kod koncipiranja budućih istraživanja ovog tipa

Automated EEG background analysis to identify neonates with hypoxic-ischemic encephalopathy treated with hypothermia at risk for adverse outcome: A pilot study

Background: To improve the objective assessment of continuous video-EEG (cEEG) monitoring of neonatal brain function, the aim was to relate automated derived amplitude and duration parameters of the suppressed periods in the EEG background (dynamic Interburst Interval= dIBIs) after neonatal hypoxic-ischemic encephalopathy (HIE) to favourable or adverse neurodevelopmental outcome. Methods: Nineteen neonates (gestational age 36-41 weeks) with HIE underwent therapeutic hypothermia and had cEEG-monitoring. EEGs were retrospectively analyzed with a previously developed algorithm to detect the dynamic Interburst Intervals. Median duration and amplitude of the dIBIs were calculated at 1h-intervals. Sensitivity and specificity of automated EEG background grading for favorable and adverse outcomes were assessed at 6h-intervals. Results: Dynamic IBI values reached the best prognostic value between 18 and 24h (AUC of 0.93). EEGs with dIBI amplitude ≥15 μV and duration 10s were specific for adverse outcome (89-100%) at 18-24h (n = 10). Extremely low voltage and invariant EEG patterns were indicative of adverse outcome at all time points. Conclusions: Automated analysis of the suppressed periods in EEG of neonates with HIE undergoing TH provides objective and early prognostic information. This objective tool can be used in a multimodal strategy for outcome assessment. Implementation of this method can facilitate clinical practice, improve risk stratification and aid therapeutic decision-making. A multicenter trial with a quantifiable outcome measure is warranted to confirm the predictive value of this method in a more heterogeneous dataset

Computational treatment of order-disorder processes by use of the cluster variation method

We present an implementation of the cluster variation method (CVM), applied to the Ising model, for computational characterization of order-disorder processes in binary systems. We show how the Newton-Raphson iteration scheme (NRIS) is used for numerical solving of system of nonlinear equations, obtained from the condition of the free energy minimum within the framework of the CVM approximation. An emphasis is made on the problem of the starting iteration point (NRIS being very sensitive to the choise of this point), for obtaining the low-temperature ordered phases. It was shown that an infinitesimally small breaking of symmetry of the high-temperature disordered phases supresses finding solutions which correspond to the metastable phases (saddle points) by NRIS (below the critical temperature T-c). This kind of problem is illustrated by an example of oxygen ordering in basal planes of YBa2Cu3O6+x system, modeled by the two-dimensional asymetric next-nearest neighbor Ising (ASYNNNI) model. Copyright (C) 1998 Elsevier Science B.V.Symposium on Computational Modeling of Issues in Materials Science at the International Conference on Applied Materials / European-Materials-Research-Society Meeting, Jun 16-20, 1997, Strasbourg, Franc

Equivalence of two parallel approaches to the cluster variation method: the multisite correlation functions method and the cluster effective fields method

We have analyzed relationship between two parallel approaches to the cluster variation method (CVM) as a theoretical tool for studying statistical properties of binary systems. The first approach to the method uses the multisite correlation functions as variational variables, while the other approach is the one that uses the cluster effective fields as variational variables. Using the Ising model description of physical systems studied, we have shown that the two approaches should produce identical final results, although they deal with quite different systems of nonlinear equations (which, in particular cases under study, must be solved numerically for a given temperature and chemical potential). To achieve identical final results, we show that it is necessary to introduce cluster fields for those clusters which appear to be subclusters of at least two different members of the Kikuchi cluster family. In addition, we demonstrate that variational variables of the two approaches generate two sets of cluster probabilities, whose intersection contains solution of the CVM approximation which corresponds to the thermodynamic equilibrium state. We also analyze the existence of the so-called consistency relations in both approaches to the CVM method, and, finally, we discuss the problem of convergency of numerical procedures that are used to analyze the low-temperature states of the model systems under study. (C) 1999 Elsevier Science B.V. All rights reserved

Distribution Of CuO Chains In The Oxygen Deficient Planes Of YBa2Cu3O6+2c

The distribution p(l) of CuO chains in YBa2Cu3O6+2c, with respect to different chain lengths l, obeys a simple exponential-low dependence p(l)=A×Bl, where the parameters A and B are functions of oxygen concentration c and temperature T. By the use of Monte Carlo numerical simulation of the ASYNNNI model, we have found that the parameters A and B can be expressed as a functions of a single parameter: average chain length lav. This dependence is established to be valid for a large number of points in the temperature-concentration plain (for the oxygen content in the range c∈(0.39,0.50), and for the temperatures extending from τ =kBT/V1≈ 0.3 to τ ≈1.8).SFKM 2004 : September 20–23, 2004, Sokobanja

The origin of the 60 K plateau in YBa(2)Cu(3)O(6+x)

A model for the charge transfer mechanism in YBa(2)Cu(3)O(6+x) high-T(c) cuprate based on the critical chain length concept is proposed to account for the 60 and 90 K plateaus in the T(c)(x) dependence. It has been shown that, when the statistics of CuO chain formation was described in terms of the two-dimensional asymmetric next-to-nearest neighbor Ising (ASYNNNI) model, at any constant temperature below the top of ortho-II phase there exists a uniquely defined value of critical chain length l(cr)(T) that yields a constant doping p(x) approximate to const over the regime of ortho-II phase (related to the 60 K plateau of T(c)(x)), while the 90 K plateau coincides with the monotonically increasing p(x) over the optimal doping level p = 0.16 in the regime of the ortho-I phase. Short length chains (l LT l(cr)(T)), together with the first l(cr)(T)-2 holes in longer chains (l GT = l(cr)(T)), are taken as not capable of attracting electrons from CuO(2) planes. It is shown that only a part (approximate to 41%) of the remaining l - l(cr)(T)+1 holes in the long chains can capture electrons. The results obtained indicate that the ASYNNNI model and two-plateau-like behavior of T(c)(x) in YBa(2)Cu(3)O(6+x) are closely connected