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A major use of DFN models for industrial applications is to evaluate permeability and flow structure in hardrock aquifers from geological observations of fracture networks. The relationship between the statistical fracture density distributions and permeability has been extensively studied, but there has been little interest in the spatial structure of DFN models, which is generally assumed to be spatially random (i.e., Poisson). In this paper, we compare the predictions of Poisson DFNs to new DFN models where fractures result from a growth process defined by simplified kinematic rules for nucleation, growth, and fracture arrest. This so-called 'kinematic fracture model' is characterized by a large proportion of T intersections, and a smaller number of intersections per fracture. Several kinematic models were tested and compared with Poisson DFN models with the same density, length, and orientation distributions. Connectivity, permeability, and flow distribution were calculated for 3-D networks with a self-similar power law fracture length distribution. For the same statistical properties in orientation and density, the permeability is systematically and significantly smaller by a factor of 1.5-10 for kinematic than for Poisson models. In both cases, the permeability is well described by a linear relationship with the areal density [ABSTRACT FROM AUTHOR]

Abstract: We present a methodology for identifying highly-localized flow channels embedded in a significantly less permeable medium using steady-state head and geometrical data. This situation is typical of fractured media where flows are often strongly channeled at the scales of interest (10m–1km). The objective is to identify both geometrical and hydraulic characteristics of the conducting structures. Channels are identified in decreasing order of importance by successive optimizations of an objective function. The identification strategy takes advantage of the hierarchical flow organization to restrict the dimension of the solution space of each individual optimization step. The characteristics of the secondary channels are strongly determined by the main flow channels. The latter are slightly modified by the secondary channels through the addition of a regularization term to the main channel characteristics in the objective function. As the objective function is strongly non-convex with numerous local minima, inversion is performed using a stochastic algorithm (simulated annealing). We assess the possibilities of the hierarchical identification strategy on simple synthetic steady-state flow configurations where hydraulic data are made up of 25 regularly spaced heads and of the boundary conditions. Those flow structures that are dominated by at most two simple channels can be identified with these head data only. Configurations comprising up to three complex and interconnected channels can still be identified with additional geometrical information including the distances of piezometers to their closest channel. The capabilities of the hierarchical identification strategy are limited to flow structures dominated by at most three equivalent flow channels. We finally discuss the perspectives of application of the method to transient-state data obtained on a more restricted number of piezometers. [Copyright &y& Elsevier]

Proton magnetic resonance spin-lattice relaxation time and second moment measurements were carried out on polycrystalline isopropylammonium bromobismuthate \[(CH3 )2 CHNH3 ]2 BiBr5 (IPBB) and bromoantimonate \[(CH ) CHNH ] SbBr (IPBA) salts over a wide temperature range. The proton spin-lattice relaxation measurements in both compounds reveal an asymmetric wide minimum due to the motions of the ammonium and methyl groups. Analysis of the relaxation data yields the activation energy barriers for the motion of the NH and CH groups. NMR data confirm the phase transitions, at 155 and 133 K for IPBB, and at 171 and 180 K for IPBA, known from previous studies. The phase transitions at 155 K in IPBB and at 180 K in IPBA are connected with freezing of the reorientation of isopropyl cations. The second moment measurements show that the structure is not rigid on the NMR scale at the lowest temperature studied, 10 K, and that CH and NH groups execute rotations about the C axis. [ABSTRACT FROM AUTHOR]

Fracture networks are preferential flow paths playing a critical role in a wide range of environmental and industrial problems. Their complex multiscale structure leads to broad distributions of fluid travel times, affecting many biogeochemical processes. Yet, the relationship between the fracture network structures, their hydrodynamic properties, and the resulting anomalous transport dynamics remains unclear. We use a large database of fracture network models to investigate the factors controlling fluid velocity and travel-time distributions across a wide range of networks, from synthetic to field-calibrated models, with aperture variability at both fracture and network scales. Analysis reveals that transport statistics have generic properties across investigated networks, including notably heavy-tailed travel time distributions. Networks of increasing complexity and heterogeneity lead to broader velocity distributions and more channeled velocity fields, where flow concentrates in a narrow channel web in the three-dimensional (3D) fracture structure. While heterogeneity in point-velocity statistics increases travel-time variability, channeling tends to reduce it. This counterintuitive phenomenon challenges current theories, which assume that long travel time power law exponents are determined solely by point-velocity statistics. By analyzing velocity and travel time statistics for different flow structures, we develop a coupled Continuous Time Random Walk framework capturing the unexpected control of the velocity field's spatial structure on anomalous transport in fracture networks. This leads to a unique class of random walk models capturing the respective roles of velocity heterogeneity and spatial structure on transport in networks. These findings open a prospective for characterizing, modeling, and predicting transport dynamics in complex networks, with potential applications to geological, biological, and engineered networks., Competing Interests: Competing interests statement:The authors declare no competing interest.

Objective: Nonylphenol is an alkylphenol compound that has been widely used in the industry. It has endocrine-disrupting properties. The effect of alkylphenol compounds on development has been the subject of a limited number of studies. Herein, we aimed to examine curcumin's effect against nonylphenol toxicity on brain development., Methods: For this study, 30 pregnant female Wistar albino rats from the Animal Laboratory of Erciyes University, Faculty of Medicine, were used. The rats were randomly divided into the following 5 groups; the control group, corn oil group (150μl/kg/day), nonylphenol group (50μl/kg/day), curcumin group (100mg/kg/day) and curcumin+nonylphenol group (100mg/kg/day+50 μl/kg/day). After the sacrification, histological and immunohistochemical evaluations were made., Results: Histopathologically, vascular congestion, increased GFAP, and p-tau immunoreactivity intensity was found in the developing brain of the nonylphenol group. Moreover, co-treatment of nonylphenol administrated with curcumin showed slight pathological alterations with vascular congestion., Conclusions: These data suggest that nonylphenol-induced increase in GFAP and p-tau immunoreactivity contributes to toxicity caused impairment in the rat brain. Additionally, curcumin had a neuroprotective effect against nonylphenol-induced neurotoxicity.

Doxorubicin (DOX) is a widely used drug for the treatment of cancer,but its clinical use is limited by its liver toxicity. Administering DOX with an antioxidant has become a strategy for preventing the side effects of DOX. Although selenium (Se) is an important trace mineral, data concerning the effect of Se on DOX induced liver tissue are lacking. We investigated the mechanism of DOX hepatotoxicity and the protective effect of different doses of Se on Dox induced liver damage. Female Wistar albino rats were divided into eight equal groups. Se was injected intraperitoneally (i.p.) to rats at doses of 0.5, 1, and 2 mg 0.5 h after injection i.p. of 5 mg/kg DOX on days 1, 7, 14, 21 and 28. Liver histopathology was assessed to determine the dose at which Se may best inhibit Dox induced liver toxicity. Also, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) expression levels and proliferating cell nuclear antigen (PCNA) activity were determined using immunohistochemistry. We found that DOX caused liver damage and increased TNF-α, IL-1β and PCNA levels. Se prevented structural damage to liver tissues. Our findings reinforce the protective effects of Se in rat liver.

The measurements of the NMR second moment can reveal information about structural and dynamical details of the sample providing that analysis of the experimental results on the basis of the Van Vleck's formula can be performed. In this paper the method of calculating the Van Vleck's second moment for solids with complex internal motions is presented. The method is based on simulating any desired motion of atoms within a block of unit cells large enough to reflect the property of the macroscopic sample and calculating the second moment value averaged by this motion. The detailed description of this method is given for the case of rotation of molecules or groups of atoms. The algorithm of the computer program which performs calculation based on the described method is also presented. Examples of application of the described method are listed.

The complexation of cyclo(Pro17O-Gly15N) and cyclo(Gly17O-Pro) with Co2+ ions has been studied by 17O, 14N and 15N n.m.r. spectroscopy in aqueous solution. 17O, 14N and 15N transverse relaxation times and chemical shifts were measured as a function of temperature. The 17O n.m.r. studies unequivocally demonstrate that the cobaltous ion binds to the peptide oxygen of both compounds. The hyperfine coupling constant and the peptide residence times were found to be A = -0.165 MHz and -0.145 MHz, tau m = 16, and 92 microseconds for cyclo(Pro17O-Gly15N) and cyclo(Gly17O-Pro), respectively. The 14N and 15N studies of labeled cyclo(Pro17O-Gly15N) do not indicate binding at either the Gly15N or the Pro14N site.

The complexation of cyclo(Ala*-Ala) with the cobaltous ions in aqueous solution was investigated by 17O and 14N n.m.r. spectroscopy. The 17O and 14N transverse relaxation time (T2p) and chemical shift (delta omega a) of cyclo(Ala*-Ala) were measured as a function of the temperature at pH = 7.03 +/- 0.02, and pH = 6.45 +/- 0.02, and as a function of pH at room temperature. No effects of pH on the transverse relaxation time and chemical shift were observed. Complementary 17O studies of the solvent water molecules were also carried out. The hyperfine coupling constant and the entropy and enthalpy of activation for the exchange of cyclo(Ala*-Ala) and water molecules between the coordinated and noncoordinated states were determined by least-square fit of theoretical equation for the chemical shift delta omega a to experimental data. The hyperfine coupling constant of the peptide bound oxygen was determined to be (-1.6 +/- 0.1) X 10(5) Hz and the entropy and enthalpy (32.0 +/- 3.0) kJ/mol and (-12.0 +/- 1.0) e.u, respectively. Information obtained from 17O n.m.r. study allows some inferences concerning the probable coordination sphere of the cobaltous ion. There are three types of complexes: Co(H2O)6(2+), CoL X 5H2O and CoL2 X 4H2O, with relative concentrations 19.9%, 2.9%, and 77.2%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

A single crystal of 17O enriched alpha-glycine was grown by slow evaporation of aqueous solution. 17O n.m.r. studies of the alpha-glycine molecule in single crystalline form revealed five 17O transitions each consisting of two lines due to inequivalency of the oxygen atoms in the unit cell, with each of these lines revealing a dipolar interaction between the 17O and the nearest hydrogen atom. The spectral width was found to be of the order of magnitude of MHz and the linewidths of the order of magnitude of 2 kHz.