Disordered kalsilite KAlSiO4

The X‐ray powder diffraction pattern that corresponds to the disordered state of kalsilite (potassium aluminium orthosilicate), KAlSiO₄, is investigated. The directionality of (Al,Si)O₄ tetrahedra within single six‐membered tetrahedral ring building units (S6R) could not be defined. With equal probability for the directionality of each tetrahedra within one S6R [free apex pointing up (U) or down (D)], an undefined sequence of U and D directionalities is needed to describe the S6R building units. The extinction conditions of disordered kalsilite are also different compared to ordered kalsilite within the space group P6₃. In disordered kalsilite, h0l and hhl reflections with l = 2n + 1 are systematically absent.     

A comparative analysis of a heat pump application with grey wastewater source for domestic hot water preparation in hotels

Journal of Thermal Analysis and Calorimetry - System for domestic hot water (DHW) preparation generally represents a considerable portion of the energy and water consumption in hotels worldwide. As...     

Degradation of azithromycin using Ti/RuO<Subscript>2</Subscript> anode as catalyst followed by DPV,HPLC–UV and MS analysis

The electrodegradation of azithromycin was studied by its indirect oxidation using dimensionally stable Ti/RuO₂ anode as catalyst in the electrolyte containing methanol, 0.05 M NaHCO₃, sodium chloride and deionized water. The optimal conditions for galvanostatic electrodegradation for the azithromycin concentration of 0.472 mg cm^?3 were found to be NaCl concentration of 7 mg cm^?3 and the applied current of 300 mA. The differential pulse voltammetry using glassy carbon electrode was performed for the first time in the above-mentioned content of electrolyte for the nine concentration of azithromycin (0.075–0.675 mg cm^?3) giving the limits of azithromycin detection and of quantification as: LOD 0.044 mg cm^?3 and LOQ 0.145 mg cm^?3. The calibration curve was constructed enabling the electrolyte analysis during its electrodegradation process. The electrolyte was analyzed by high-performance liquid chromatography and electrospray ionization time-of-flight mass spectrometry. The electrooxidation products were identified and after 180 min there was no azithromycin in the electrolyte while TOC analysis showed that 79% of azithromycin was mineralized. The proposed degradation scheme is presented.     

Optimization of cubic GaN/AlGaN quantum cascade structures for negative refraction in the THz spectral range

In this work we theoretically investigate a possibility to use cubic nitride based multi-layer periodic nanostructure as a semiconductor metamaterial. The structure design is based on an active region of a quantum cascade laser optimized to achieve optical gain in the Terahertz (THz) spectral range. In particular, we test the GaN/AlGaN quantum well configurations, which should exhibit important advantages compared to GaAs-based structures, namely room temperature operation without the assistance of magnetic field and lower doping densities. Our numerical rate-equations model is solved self-consistently and it takes into account electron-longitudinal optical phonon scattering between all the relevant states among the adjacent periods of the structure. A global optimization routine, specifically genetic algorithm is then used to generate new gain-optimized structures. This work confirms the advantages of cubic GaN designs over GaAs ones, namely feasibility of negative refraction at room temperature without the assistance of magnetic field while keeping the doping densities of the same order of magnitude.     

Identifying Criteria of Identity

I discuss E. J. Lowe’s conception of criteria of identity and sketch a different and, I think, more adequate conception. On my view, criteria of identity are some of the things we can do. They are what we do when distinguishing between single entities of the kind in question and pairs of entities of the relevant domain. And they enable us to make such distinctions because they are applicable to all single and to all pairs of entities of the relevant domain but fulfilled only by all single entities of the kind in question. This feature of criteria of identity allows us to define these criteria, to explain how to identify a particular criterion of identity and to determine the logical form in which to express such identifications.