The pin power distribution in theVVER-1000 mock-up on the LR-0 research reactor

The pin power density distribution in reactor is an important quantity, necessary for the adequate assessment of fuel conditions and of core structures and pressure vessel radiation embrittlement as well.The paper shows the detailed comparison of calculated and experimentally determined pin by pin power distribution. To verify the reliability of measured data used for comparison with calculated data, the symmetrically located pins were measured. The calculations have been done with deterministic and Monte Carlo approach. The effect of different data libraries used for calculations are discussed as well.     

Optimization of the spark plasma sintering processing parameters affecting the properties of polyimide

The present study deals with the optimization of polyimide (PI) mechanical properties, obtained by Spark Plasma Sintering (SPS), by using a method combining Design of Experiments (DOE) with physical, structural, and mechanical characterizations. The effects of SPS parameters such as temperature, pressure, dwell time, and cooling rate on the density, mechanical properties, and structure of PI were investigated. The experimental results revealed that the mechanical properties of the material were optimized by raising the sintering temperature up to 350°C. The optimized SPS processing parameters were a temperature of 350°C, a pressure of 40 MPa, and a dwell time of 5 min. Under these conditions, a relative density of 99.6% was reached within only a few minutes. The corresponding mechanical properties consisted of Young's modulus of 3.43 GPa, a Shore D hardness of 87.3, and a compressive strength of 738 MPa for a maximum compressive strain of 61.8%. Moreover, when working at 320°C and at 100 MPa, an increase in the dwell time was necessary to enhance the properties. Contrary to the other parameters, the cooling rate appeared to be a non‐significant parameter. Finally, correlations between the PI structure and the mechanical properties were made to demonstrate the densification mechanisms. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41542.     

Strategies in environmental education

The causes of environmental changes, including climate, are neither fully understood nor identified, nor do scientists agree about their nature. Yet, their impact is such that action cannot be delayed. This involves spreading public awareness through environmental education and sensitization. Hence a need to reach, to educate the poorly informed public at large. With the classroom as the base, “town meetings” and eco‐tourism may constitute potentially useful approaches towards that goal.     

An assessment of briefs used for designing healthcare environments: a survey in Sweden

The brief is a central document in decision-making during the early stages of the planning and construction (briefing/programming) of healthcare environments. Thus, the demand on the content and quality of these documents is high. The content and quality of initial briefs developed in Sweden were assessed to obtain an up-to-date picture of current practices of writing project statements in the early stages of designing healthcare environments. A new instrument called the Content and Quality of Brief Instrument (CQB-I) was used to study 29 initial briefs. In many cases, the documentation in the briefs was incomplete and the information did not adequately address users’ needs. In addition, the briefs often did not include any measurable outcomes or explicitly evidence-based information. These findings have implications for identifying areas for improvement in design teams’ documentation practices. Assessment can have a real impact on the quality of briefs and can raise awareness of the need to improve the briefing process itself. This is one of the first studies to assess the content and quality of briefs and it provides a starting point for both practitioners and future researchers to explore the role of briefs in briefing process quality improvement.     

AND SO ON,AND

…aporia is not something negative, not something which in fact paralyses us. but on the contrary it is an ordeal, a test, a crucial moment through which we have to go, even if we are stuck, we have to experience this moment of aporia in order to make a decision, in order to take responsibility, in order to have a future, and so on and so forth.¹     

Renewable thermoplastic multiphase systems from dimer fatty acids,with mineral microfillers

Renewable thermoplastic blends based on polyurethane (TPU) and polyamide (DAPA) obtained from dimers of fatty acids were reinforced with mineral microfillers, surface coated calcium carbonate (CaCO₃) or high aspect ratio talc (HAR), to prepare different micro‐biocomposites systems. The influence of the nature of the filler, the aspect ratio and the filler content (5, 10, and 15 wt %), for different TPU/DAPA ratios (20/80, 50/50, and 80/20 wt %/wt %), were specifically investigated. Differential scanning calorimetry (DSC) and thermogravimetric analyses were conducted to investigate the thermal properties. DSC analyses showed that the addition of CaCO₃ had no influence on the glass transition and the melting temperature of the corresponding composites. Moreover, the morphology and the mechanical properties in the solid state of the different multiphase systems were investigated. SEM observations after tensile tests showed that the best matrix/filler interactions were obtained in the case of the 20/80‐based systems. Uniaxial tensile tests have shown that the addition of HAR or CaCO₃ fillers led to a clear increase of the Young modulus. Micromechanical models based on a two‐phase composite approach, including Mori–Tanaka and Davies models were used to describe the dependence of the elastic modulus on the volume fraction of HAR or CaCO₃ fillers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43055.     

Nanocomposites of PBAT and cellulose nanocrystals modified by in situ polymerization and melt extrusion

Cellulose nanocrystals (CNC) were successfully grafted with a low molecular weight poly(butylene glutarate) through an in situ polymerization procedure. The grafting treatment decreased the CNC hydrophilic character and increased the onset of their thermal degradation by approximately 20°C, thus increasing the possibilities of CNC application. Composites of grafted and nongrafted CNC with a poly(butylene‐adipate‐co‐terephthalate) (PBAT) matrix were prepared by melt extrusion. The CNC addition led to an increase of 50% of the tensile elastic modulus of the PBAT. In addition, dynamic mechanical thermal analysis showed that the composite with CNC retained its high modulus even at temperatures far above the glass transition temperature of PBAT. At 60°C the storage modulus of the composite with CNC was approximately 200% higher than that of the pure PBAT. Thus, in this work, nanocomposites of improved properties were obtained through a combination of in situ polymerization and melt extrusion. POLYM. ENG. SCI., 56:1339–1348, 2016. © 2016 Society of Plastics Engineers     

Enhanced O2 Flux of CaTi0.85Fe0.15O3−δ Based Membranes by Mn Doping

Dense symmetric membranes of CaTi_0.85?xFe_0.15Mn_xO_3?δ (x = 0.1, 0.15, 0.25, 0.4) are investigated in order to determine the optimal Mn dopant content with respect to highest O₂ flux. O₂ permeation measurements are performed as function of temperature between 700°C–1000°C and as function of the feed side ranging between 0.01 and 1 bar. X‐ray photoelectron spectroscopy is utilized to elucidate the charge state of Mn, and synchrotron radiation X‐ray powder diffraction (SR‐XPD) is employed to investigate the structure symmetry and cell volume of the perovskite phase at temperatures up to 800°C. The highest O₂ permeability is found for x = 0.25 over the whole temperature and ranges, followed by x = 0.4 above 850°C. The O₂ permeability for x = 0.25 reaches 0.01 mL(STP) min^?1 cm^?1 at 925°C with 0.21 bar feed side and Ar sweep gas. X‐ray photoelectron spectroscopy indicates that the charge state of Mn changes from approx. +3 to +4 when x > 0.1, which implies that Mn mainly improves electronic conductivity for x > 0.1. The cell volume is found to decrease linearly with Mn content, which coincides with an increase in the activation energy of O₂ permeability. These results are consistent with the interpretation of the temperature and dependency of O₂ permeation. The sintering behavior and thermal expansion properties are investigated by dilatometry, which show improved sinterability with increasing Mn content and that the thermal expansion coefficient decreases from 12.4 to 11.9 × 10^?6 K^?1 for x = 0 and x = 0.25, respectively.     

Current Understanding of Structure–Processing–Property Relationships in BaTiO3–Bi(M)O3 Dielectrics

As part of a continued push for high permittivity dielectrics suitable for use at elevated operating temperatures and/or large electric fields, modifications of BaTiO₃ with Bi(M)O₃, where M represents a net‐trivalent B‐site occupied by one or more species, have received a great deal of recent attention. Materials in this composition family exhibit weakly coupled relaxor behavior that is not only remarkably stable at high temperatures and under large electric fields, but is also quite similar across various identities of M. Moderate levels of Bi content (as much as 50 mol%) appear to be crucial to the stability of the dielectric response. In addition, the presence of significant Bi reduces the processing temperatures required for densification and increases the required oxygen content in processing atmospheres relative to traditional X7R‐type BaTiO₃‐based dielectrics. Although detailed understanding of the structure–processing–property relationships in this class of materials is still in its infancy, this article reviews the current state of understanding of the mechanisms underlying the high and stable values of both relative permittivity and resistivity that are characteristic of BaTiO₃‐Bi(M)O₃ dielectrics as well as the processing challenges and opportunities associated with these materials.     

The Change of X‐ray Diffraction Peak Width During in situ Conventional Sintering of Nanoscale Powders

Diffraction peaks of nanoscale particles of 3 mol% yttria‐stabilized zirconia become sharper as the powder sinters. The reduction in the peak width is correlated with the increase in density. The sharpening of the peak agrees reasonably well with the remaining free surface area as the sample sinters. Therefore, high curvature of the free surface of the pores is assumed to lead to peak broadening (the grain boundaries that grow at the expense of the free surfaces of the pores do not have this curvature). The change in the grain size during sintering does not make a significant contribution to peak width.