Based on the results of the infrared thermography of 51 artificially created defects - voids and delaminations - in concrete, it was shown that it is possible to detect defects at depths that are equal or less than the defect size D using the thermal contrast method. By applying the phase contrast method, an increase of 50% in the maximum depth for a given defect size D was achieved. Delaminations containing thin air gaps were detected with the same success as much larger voids of the same cross section.
COBISS.SI-ID: 7065697
Terahertz (THz) spectroscopy and imaging is used to analyse different types of thermal building insulation materials. First, the absorption coefficients of polymer foams are calculated, showing an inverse relationship with thermal conductivity. In addition, manufacturing imperfections and internal structures within the foams are clearly visualized with THz amplitude imaging. Secondly, different fibre orientations within aerogel composite blanket are recognized in THz spectra and amplitude images. Lastly, the phase transition of microencapsulated phase-change material is indicated by occurrence of spectral peaks in THz spectrum. The selected method is promising for a non-destructive testing of the thermal insulation material properties and structure.
COBISS.SI-ID: 28983847
In last two decades, rapid development in the field of terahertz (THz) technology has opened new possibilities for creating innovative imaging and sensing systems. Although the applications of THz technology in different sectors constantly increase, the construction industry lags behind them. The aim of this article is to review the current applications of THz spectroscopy in research and industry related to construction and building materials, along with the key drawbacks of technology and recommendations for future use. We demostrateted that THz spectroscopy and imaging have promising potential and provide many opportunities for applications in construction and building materials characterization.
COBISS.SI-ID: 28098599
A new polymorphic crystal form of piroxicam was discovered while preparing crystalline samples of piroxicam for 14N nuclear quadrupole resonance (NQR) analysis. The new crystal form, designated as V, was prepared by evaporative recrystallization from dichloromethane. Three known polymorphic forms (I, II, and III) were also prepared. Our aim was to apply 14N NQR to characterize the new polymorphic form of piroxicam and compare the results with those of the other known polymorphic forms. Additional analytical methods used for characterization were X-ray powder diffraction (XRPD), thermal analysis, and vibrational spectroscopy. For the first time, a complete set of nine characteristic 14N NQR frequencies was found for each prepared polymorph of piroxicam. The consistent set of measured frequencies and calculated characteristic quadrupole parameters found for the new polymorphic form V is a convincing evidence that we are dealing with a new form. The already known piroxicam polymorphic forms were characterized similarly. The XRPD results were in accordance with the conclusions of 14N NQR analysis. The performed study clearly demonstrates a strong potential of 14N NQR method to be applied as a highly discriminative spectroscopic analytical tool to characterize polymorphic forms.
COBISS.SI-ID: 17286233
Diluted magnetic semiconductors possessing intrinsic static magnetism at high temperatures represent a promising class of multifunctional materials with high application potential in spintronics and magneto-optics. In the hexagonal Fe-doped diluted magnetic oxide, 6H-BaTiO3, room-temperature ferromagnetism has been previously reported. Our results demonstrate that the intricate static magnetism of the hexagonal phase is not intrinsic, but rather stems from sparse strain-induced pseudocubic regions. We point out the vital role of internal strain in establishing defect ferromagnetism in systems with competing structural phases.
COBISS.SI-ID: 28275751