Calculating Bond-Stretching Force Constant of Binary Cubic Semiconductors and Ionic Materials Using a Simple Theoretical Approach

The vibrational dispersion relation of solid linear lattice of diatomic primitive cell, taking to account only the nearest-neighbor interaction between atoms, after generalizing it to become expressive of the three-dimensional one, was used to obtain a mathematical relation connecting the interatomic bond stretching force constant with the bulk modulus and the equilibrium lattice constant for ANB8-N binary semiconductors and binary ionic materials (monatomic ones automatically included).The analytical approach was supported by computer statistical adjustment, and the accuracy of the obtained mathematical formula was confirmed by comparing it with many values reported by other researchers with large number of materials of different groups, each of whom got a mathematical relation that differs from those of the others

Effect of starting materials on the structure of pure and Gd-doped BaTiO3 elaborated by the sol gel process

Undoped and Gd-doped BaTiO3 samples, with the chemical formula BaGdxTi1-xO3-x/2□x/2, x = 0.00; 0.01; 0.02; 0.03; 0.04 and 0.05, were synthesized using the sol gel process. During the procedure of preparation of these samples acetic acid and distilled water were used as solvents. All the powders corresponding to the two series of undoped and doped samples were calcined in air at different temperatures and their crystalline phase was checked using results from XRD and Raman analyses. Acetic acid was shown to provoke the formation of the stable pseudo cubic structure for the two series of samples at relatively low temperature of crystallization, while with the use of distilled water only (without acetic acid) the tetragonal phase prevailed. In this study, the effect of acetic acid is discussed and the latter seems to play a more or less important role in the formation of the structure of BT material

Effective flow and transport properties of heterogeneous unsaturated soils

The heterogeneity of field scale soils poses a challenge to predictive large scale flow and transport modeling. The theory of effective macroscale parameters holds good and is applicable in dealing with such problems. But the va- lidity of the analytic stochastic solutions obtained for randomly heterogeneous soils is debatable, as the test cases under which they are validated are of limited scope due to linearization and perturbation approximations. In this study, samples of heterogeneous soils are generated using sets of spatially correlated random field parameters that are either geometrically isotropic, or else, geometrically anisotropic with either horizontal or vertical stratifi- cation (perfect or imperfect). Several combinations of ratios of correlation length and capillary dispersion lengths are considered. Numerical simulations of unsaturated flow are performed on each randomly heterogeneous soil sample. The principal components ̂K ii (Ψ) of the macroscale effective unsaturated conductivity are then obtained as a function of the mean suction Ψof the sample. They are compared to stochastic spectral perturbation theory, and to a probabilistic semi-empirical Power Average Model (PAM). They are also compared with arithmetic, geo- metric and harmonic mean conductivity-suction curves. The numerically upscaled principal conductivity curves match quite well the PAM, better than the classical means (Arithmetic, Geometric, Harmonic), and also some- what better than the curves obtained from stochastic spectral perturbation theory. It is observed that the upscaled principal components K ii ( ????), obtained numerically and with the PAM along directions “i ”orthogonal/parallel to perfect stratification coincide with the harmonic/arithmetic mean curves at low suctions (i.e., near saturation), but deviate from it and come closer to the geometric mean at higher suctions. The PAM appears suitable for generation of approximate upscaled conductivity curves, e.g., for obtaining the mesh-scale or block-scale con- ductivity curves in large scale simulation codes. Transient solute transport simulations are then performed on the detailed random velocity fields obtained from the steady state simulations of unsaturated flow in the randomly heterogeneous soil samples. Snapshots of solute concentration C(x,z,t) are taken at different times. The temporal evolution of spatial moments of concentration is analyzed in order to characterize the macroscale advection and dispersion of the unsaturated concentration plume, and in particular, its macro-dispersion coefficient (D) and dis- persivity length scale (A). For the synthetic soil samples considered in this study, the macro-dispersive spreading of the solute is stronger for flow parallel to vertical stratification, compared to flow perpendicular to horizontal stratification, and also, compared to flow in statistically isotropic non-stratified soil

EFFECT OF SALINITY ON THE PHYSIOLOGICAL BEHAVIOR OF THE OLIVE TREE (VARIETY SIGOISE

Salinity is a major problem directly affecting the ecological balance and the development of agriculture in the Mediterranean basin, particularly North Africa. This phenomenon is considered as the most important abiotic factor limiting crops growth and productivity, degrading and polluting soils in arid and semi-arid. In order to study the influence of salinity, on the physiological parameters and to assess the potential of adaptation of the olive tree in a saline environment, three parcels containing the Sigoise variety and subject to different degrees of salinity were selected: Parcel 1 (non-saline); Parcel 2 (saline); Parcel 3 (very saline). Under a saline constraint, the results showed two contrasting tendencies, an intense increase in the content of proline, sodium (Na+) and chlorophyll (b), while water content, potassium and chlorophyll (a) decreased strongly with increasing salinity

An open source massively parallel solver for Richards equation: Mechanistic modelling of water fluxes at the watershed scale

In this paper we present a massively parallel open source solver for Richards equation, named the RichardsFOAM solver. This solver has been developed in the framework of the open source generalist computational fluid dynamics tool box OpenFOAM® and is capable to deal with large scale problems in both space and time. The source code for RichardsFOAM may be downloaded from the CPC program library website. It exhibits good parallel performances (up to ∼90% parallel efficiency with 1024 processors both in strong and weak scaling), and the conditions required for obtaining such performances are analysed and discussed. These performances enable the mechanistic modelling of water fluxes at the scale of experimental watersheds (up to few square kilometres of surface area), and on time scales of decades to a century. Such a solver can be useful in various applications, such as environmental engineering for long term transport of pollutants in soils, water engineering for assessing the impact of land settlement on water resources, or in the study of weathering processes on the watersheds

An Activation Force-based Affinity Measure for Analyzing Complex Networks

Affinity measure is a key factor that determines the quality of the analysis of a complex network. Here, we introduce a type of statistics, activation forces, to weight the links of a complex network and thereby develop a desired affinity measure. We show that the approach is superior in facilitating the analysis through experiments on a large-scale word network and a protein-protein interaction (PPI) network consisting of ∼5,000 human proteins. The experiment on the word network verifies that the measured word affinities are highly consistent with human knowledge. Further, the experiment on the PPI network verifies the measure and presents a general method for the identification of functionally similar proteins based on PPIs. Most strikingly, we find an affinity network that compactly connects the cancer-associated proteins to each other, which may reveal novel information for cancer study; this includes likely protein interactions and key proteins in cancer-related signal transduction pathways

Two-dimensional NMR lineshape analysis

NMR titration experiments are a rich source of structural, mechanistic, thermodynamic and kinetic information on biomolecular interactions, which can be extracted through the quantitative analysis of resonance lineshapes. However, applications of such analyses are frequently limited by peak overlap inherent to complex biomolecular systems. Moreover, systematic errors may arise due to the analysis of two-dimensional data using theoretical frameworks developed for one-dimensional experiments. Here we introduce a more accurate and convenient method for the analysis of such data, based on the direct quantum mechanical simulation and fitting of entire two-dimensional experiments, which we implement in a new software tool, TITAN (TITration ANalysis). We expect the approach, which we demonstrate for a variety of protein-protein and protein-ligand interactions, to be particularly useful in providing information on multi-step or multi-component interactions

From Profile to Surface Monitoring: SPC for Cylindrical Surfaces Via Gaussian Processes

Quality of machined products is often related to the shapes of surfaces that are constrained by geometric tolerances. In this case, statistical quality monitoring should be used to quickly detect unwanted deviations from the nominal pattern. The majority of the literature has focused on statistical profile monitoring, while there is little research on surface monitoring. This paper faces the challenging task of moving from profile to surface monitoring. To this aim, different parametric approaches and control-charting procedures are presented and compared with reference to a real case study dealing with cylindrical surfaces obtained by lathe turning. In particular, a novel method presented in this paper consists of modeling the manufactured surface via Gaussian processes models and monitoring the deviations of the actual surface from the target pattern estimated in phase I. Regardless of the specific case study in this paper, the proposed approach is general and can be extended to deal with different kinds of surfaces or profiles