Evidence for a crystal-amorphous interphase in PVDF and PVDF/PMMA blends

Dielectric relaxation studies and absolute small-angle X-ray investigations give evidence that amorphous interlamellar regions in partially crystalline PVDF/PMMA blends consist of two phases: a pure amorphous PVDF phase and a homogeneously mixed PVDF/PMMA phase. The local phase separation which occurs, despite favourable interactions between PMMA and PVDF, is attributed to a PVDF crystal-amorphous interphase which rejects PMMA segments. The thickness of this interphase is found to be of the order of 2.5 nm.     

Preparation and properties of cubic ZrO2 stabilized with Ni(II)

Samples of cubic stabilized ZrO₂ have been prepared by the code-composition of nickel nitrate and zirconyl nitrate at 500°C. A comparison of the stability towards reduction of the bulk NiO and the Ni(II) in the cubic stabilized ZrO₂ deomstrates the influence of the stabilization of cubic ZrO₂ with Ni(II).     

Supervisory control and data acquisition (SCADA) reliability and availability improvement when state estimation and automatic testing are used

The reliability of power system supervisory control and data acquisition (SCADA) facilities improves from 0.9010 to 0.9818 and from 0.9010 to 0.9420 respectively when state estimation and automatic testing are used at the control centre instead of regular preventive maintenance inspections on-site. No significant increase in manpower is required to achieve these extremely high availabilities. The measurements obtained by SCADA are normally selected for operational reasons and so they usually have redundancy. Utilities can significantly improve the control centre availability simply by using state estimation and automatic testing on-line.     

Phase formation in Al2O3-C refractories with Al addition

Depending on the recipe and the firing conditions, several non-oxides can be formed in Al₂O₃-C refractories. In this paper, the effect of the purity of the recipe components on the phase formation in Al₂O₃-C refractories with Al addition was investigated. Two test series were sintered from 800 °C to 1600 °C under air embedded in coke breeze. One test series was with brown fused alumina, and the other was with tabular alumina. At temperatures of up to 1200 °C the phase formation was the same for both recipes. For temperatures greater than 1400 °C, the impurities of brown fused alumina enhanced the formation of a polytype, while Al₄O₄C and Al₂₈O₂₁C₆N₆ were formed in the other series. The findings explain the occurrence of several non-oxides in disequilibrium at the chosen temperatures. The occurrence of Al₄C₃ was of particular interest due to its low hydration resistance. It was formed at 1200 °C.     

Geometrical nonlinear free vibration analysis of FGM spherical panel under nonlinear thermal loading with TD and TID properties

In this article, the nonlinear free vibration behavior of functionally graded (FG) spherical shell panel is examined under nonlinear temperature field. The functionally graded material (FGM) constituents are assumed to be the function of temperature and the thermal conductivity. The effective \hboxmaterial properties of the FGM are obtained using the Voigt micromechanical model through power-law distribution. The mathematical model of the shell panel is developed using Green–Lagrange nonlinear kinematics in the framework of the higher order shear deformation theory. The desired governing \hboxequation of the FG shell panel under thermal environment is obtained using the classical Hamilton's principle. The domain is discretized with the help of the \hboxisoparametric finite element steps and the responses are computed using the direct \hboxiterative method. The convergence behavior of the present nonlinear numerical model has been checked and compared with the previous reported results. Numerous examples have been demonstrated for the FG spherical panel to show the influence of different geometrical and material parameters and support conditions on the linear and nonlinear frequency parameters.     

Designing low-carbon MgO–Al2O3–La2O3–C refractories with balanced performance for ladle furnaces

In order to achieve high-quality and stable production of special steel, the performance of low-carbon MgO-C refractories needs to be further optimized. For this purpose, low-carbon MgO–Al₂O₃–La₂O₃–C refractories with enhanced thermal shock resistance and slag resistance were designed and successfully prepared by introducing Al₂O₃ as a reinforcer and La₂O₃ as a modifier. The results showed that the refractory samples with additives show better overall performance than those without additives. When 10 wt% of Al₂O₃ and La₂O₃ were added, the oxidation resistance, thermal shock resistance and slag resistance of the refractory samples coked at 1400 °C are increased by 13.57%, 17.75% and 43.09%, respectively. The analysis found that this can be mainly attributed to the formation of MgAl₂O₄, Mg₂SiO₄, and 2CaO·4La₂O₃·6SiO₂ and the consequent volume expansion effect and intergranular phase enhancement effect. Therefore, a low-cost and enforceable reinforcement strategy for low-carbon MgO-C refractories is proposed, which is expected to be applied in steelmaking.     

Variability of waste copper slag concrete and its effect on the seismic safety of reinforced concrete building: A case study

Proven research output on the behavior of structures made of waste copper slag concrete can improve its utilization in the construction industry and thereby help to develop a sustainable built environment. Although numerous studies on waste copper slag concrete can be found in the published literature, no research has focused on the structural application of this type of concrete. In particular, the variability in the strength properties of waste copper slag concrete, which is required for various structural applications, such as limit state design formulation, reliability-based structural analysis, etc., has so far not attracted the attention of researchers. This paper quantifies the uncertainty associated with the compressive-, flexural- and split tensile strength of hardened concrete with different dosages of waste copper slag as fine aggregate. Best-fit probability distribution models are proposed based on statistical analyses of strength data generated from laboratory experiments. In addition, the paper presents a reliability-based seismic risk assessment of a typical waste copper slag incorporated reinforced concrete framed building, considering the proposed distribution model. The results show that waste copper slag can be safely used for seismic resistant structures as it results in an identical probability of failure and dispersion in the drift demand when compared with a conventional concrete building made of natural sand.     

Synthesis and properties of thin film polymorphs of molybdenum trioxide

Thin film polymorphs of molybdenum trioxide have been synthesized by reactive r.f. sputtering in an atmosphere of argon plus oxygen. Films deposited on thermally insulated substrates are polycrystalline and exhibit preferred orientation. Depending on the oxygen partial pressure P_O2 during sputtering, the films crystallize in either the thermodynamically stable α-MoO₃ form (P_O2 ≈ 50%) (unique two-dimensional layered structure) or the newly discovered, metastable monoclinic β-MoO₃ phase (P_O2 ≈ 10%) (three-dimensional ReO₃-related structure). Metastable β films convert thermally to the α phase and the transformation appears topotactic. In contrast, films deposited on cooled substrates are amorphous. A correlation between the particular phase formed and adatom mobility is noted.     

The chemical characterization of some Astragalus gum exudates

Samples of the gum exudates from five Asiatic Astragalus species, grown in the USA, have been completely characterized. The data extend those previously available for only three named Astragalus species and confirm the previous belief, based on the great variability of commercial gum tragacanth shipments, that the genus Astragalus is extremely complex and variable. The analytical parameters that predict the various commercial functionalities of gum tragacanth are not well defined but, for functionality that depends solely on viscosity, the principal Astragalus species tapped in Iran and Turkey, A.microcephalus (not A.gummifer), appears to be well chosen.