Constitutive laws for the neutron density current

In this technical note, a fractional wave equation for the average neutron motion in nuclear reactor is considered. This representation covers the full spectrum of the average neutron transport behavior, i.e., Fickian and non-Fickian effects. The fractional diffusion model retains the main dynamic characteristics of the neutron motion in which the relaxation time associated with a rapid variation in the neutron flux contains a fractional exponent that can be manipulated to obtain the best representation of the neutron transport phenomena. The detrended fluctuation analysis (DFA) method is presented in this paper to estimate the fractional exponent.     

Bioaccessible selenium in Italian agricultural soils: Comparison of the biogeochemical approach with a regression model based on geochemical and pedoclimatic variables

Biogeochemical mapping of selenium in Italian agricultural soils was accomplished by measuring the Se concentration of representative samples of wheat grains from 71 provinces. The range of the concentration values averaged on a provincial basis was 7-245 ng Se g(-1). A multiple regression model based on six geochemical and pedoclimatic variables was developed to interpret the observed data and to predict Se concentration of wheat in areas where analytical data were missing and in the different Italian soil regions. The statistical model explained only part of the observed variance, but succeeded in identifying Se-enriched as well as Se-depleted areas with an acceptable level of agreement with the biogeochemical map based on measured Se in wheat. Furthermore, the model showed that within the range of concentrations measured in Italian soils, Se-bioaccessibility is controlled not only by the Se content of the soil parent rocks, but also by their overall geochemical nature (carbonatic vs. silicatic) and by pedoclimatic variables (temperature and rain intensity excursions) related to fluctuations of soil moisture and pH. Overall, several Se-marginal and Se-deficient areas were identified on the Italian territory. The implications of these findings for public health are discussed briefly.     

Poled Polyaniline Coated Piezo Composite Using Low Electric Field and Reduced Poling Time： A Functional Material

Composite films were prepared by two different routes： lead zirconate titanate （PZT） particles coated with polyaniline （PAni） dispersed in a polymeric matrix of polyvinylidene fluoride （PVDF）; and PZT particles and PAni powder dispersed separately in the polymer matrix. The electrical conductivity of the particles was controlled by the protonation and de-protonation of PAni in solution with controlled pH. The results indicate that the percolation threshold of the composite made of PZT coated with a conductive layer （PZT-PAni） is in the range of 20 vol.% to 30 vol.% of PZT-PAni. The PZT-PAni/PVDF composite redoped in solution with pH 3.7 showed the best results in terms of longitudinal piezoelectric coefficient （d33） in samples containing 30 vol.% of ceramic particles due to the equilibrium between conduction and poling effects on the composite. The poling process of the composite sample required just 5 MV/m electric field applied during 15 min. Furthermore, the composite was used as sensor in structural health monitoring （SHM）, showing the possibility to propose it as a functional material.     

Stakeholder management influence on trust in a project: A quantitative study

This article aims to analyze the influence of stakeholder management on trust in project environments. Data was collected from 130 project professionals in companies from several national and multinational segments operating in Brazil. PLS-PM was applied for treatment and for data analysis. The results show that the relational stakeholder management influence on the three types of trust is relevant and significant. Therefore, it is important that the project manager not fail to consider actions such as communication with empathy as of the beginning of the project.