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In this article the possibility of heat accumulator use in one of the buildings of SPBSTU was analyzed. The use of this accumulator could lower the hot water demand. To complete the goal it was assumed that there is an additional café with defined working hours. Different kinds of heat collecting materials were studied: water, red brick, concrete and granite. Depending on charging time of the heat accumulator, the results of the heat gaining abilities of different materials were made. As a result it was calculated that single-phased accumulating materials should not be used as heat collectors in public buildings.

Hybrid materials of inorganic-organic phases in which each phase provides different functionality are attractive candidates for achieving multifunctionality. Using a layer-by-layer approach, we fabricated sheets of piezoelectric polymer P(VDF-TrFE) reinforced by aligned sub-micron thick sapphire platelets. The films were transparent and piezoelectric, exhibited ductility up to ≈330%, and tensile toughness of up to 26 J g-1. We investigated the effect of thermal annealing on the crystallinity of the polymer phase and its effect on the mechanical and piezoelectric properties of the films. Thermal annealing resulted in improvement of the elastic modulus and piezoelectric properties of the films. in situ SEM tensile experiments were conducted for observation of the deformation mechanism of the films. [ABSTRACT FROM AUTHOR]

Ion irradiation effects on thermal property changes are compared between aligned carbon nanotube (A-CNT) films and randomly entangled carbon nanotube (R-CNT) films. After H, C, and Fe ion irradiation, a focusing ion beam with sub-mm diameter is used as a heating source, and an infrared signal is recorded to extract thermal conductivity. Ion irradiation decreases thermal conductivity of A-CNT films, but increases that of R-CNT films. We explain the opposite trends by the fact that neighboring CNT bundles are loosely bonded in A-CNT films, which makes it difficult to create inter-tube linkage/bonding upon ion irradiation. In a comparison, in R-CNT films, which have dense tube networking, carbon displacements are easily trapped between touching tubes and act as intertube linkage to promote off-axial phonon transport. The enhancement overcomes the phonon transport loss due to phonon-defect scattering along the axial direction. A model is established to explain the dependence of thermal conductivity changes on ion irradiation parameters including ion species, energies, and current. [ABSTRACT FROM AUTHOR]

Single crystals of Pr2Fe(4-x)Co(x)Sb5 (1 < x < 2.5) were grown from a Bi flux and characterized by X-ray diffraction. The compounds adopt the La2Fe4Sb5 structure type (I4/mmm). The structure of Pr2Fe(4-x)Co(x)Sb5 (1 < x < 2.5) contains a network of transition metals forming isosceles triangles. The x ∼ 1 analogue is metallic and exhibits a magnetic transition at T1 ≈ 25 K. The magnetic moment obtained from the Curie-Weiss fit is 11.49(4) μ(B), which is larger than the spin-only Pr(3+) moment. The x ∼ 2 analogue orders magnetically at T1 ≈ 80 and T2 ≈ 45 K. This is the first case of the substitution of Co into the La2Fe4Sb5 structure type, evidenced by the increased concentration of dopant with decreased lattice parameters coupled with a change in the transition temperature with a change in the cobalt concentration. The added complexity in the magnetic behavior of the x ∼ 1 and 2 analogues indicates that the increased concentration of Co invokes an additional magnetic contribution of the transition metal in the sublattice. Furthermore, X-ray photoelectron spectroscopy measurements support the change in the oxidation states of transition metals with increasing cobalt concentration.