Tip-enhanced Stokes and anti-Stokes Raman scattering in defect-enriched carbon films

Anti-Stokes Raman scattering is one of the mechanisms that lie behind an optical refrigeration due to release of photons with greater energy than of incoming photons. To achieve a cooling regime the enhancement of anti-Stokes scattering is necessary, since spontaneous Stokes scattering dominates over anti-Stokes scattering under normal conditions. Here, we investigate the opportunity of enhancement of spontaneous anti-Stokes Raman scattering in defect-enriched carbon film by means of localized plasmon resonances. In our simulations, incoherence of Raman scattering results in excess of anti-Stokes intensity over Stokes one. However, when the field is localized within the phonon coherence volume (coherent regime), the anti-Stokes intensity is lower compared to Stokes one. The provided analysis shows that plasmon-enhanced anti-Stokes Raman scattering can be achieved in highly-defective carbon films. The results are beneficial for Raman-based temperature measurements on the nanoscale.

Decrease of Leidenfrost temperature at quenching in subcooled liquids

Cooling of high-temperature bodies in liquids largely depends on its subcooling to the saturation temperature. An increase in subcooling leads to an increase in the surface temperature, at which the vapor film loses its stability and an intensive cooling regime begins. This temperature depends on a number of parameters, such as the properties of a liquid and a solid, the composition and topology of the surface, the value of subcooling. Within the framework of this work, it was possible to achieve a significant decrease in the temperature of the onset of an intensive cooling mode in subcooled water and ethanol by using as working sections of metal samples with a high of thermal effusivity, low roughness and a protective coating from oxidation. The obtained experimental results confirm the approximate model of the appearance of an intense cooling regime

Development of a Mosque Design for a Hot, Dry Climate Based on a Holistic Bioclimatic Vision

Over 50% of the total energy consumed by buildings in a hot and dry climate goes toward the cooling regime during the harsh months. Non-residential buildings, especially houses of worship, need a tremendous amount of energy to create a comfortable environment for worshipers. Today, mosques are regarded as energy-hungry buildings, whereas in the past, they were designed according to sustainable vernacular architecture. This study was aimed at improving the energy performance of mosques in a hot and dry climate using bioclimatic principles and architectural elements. To achieve this aim, a process-based simulation approach was applied together with a generate and test technique on 86 scenarios based on 10 architectural elements, with various arithmetic transition rates organized in 9 successive steps. Starting from a simplified hypothetical model, the final model of the mosque design was arrived at based on a holistic bioclimatic vision using 10 architectural elements. The findings of this research were limited to a specific mosque size in a hot and dry climate, but the proposed holistic bioclimatic concept can be developed to take into account all mosque models in several harsh environments.

Effect of the Cooling Regime on the Mineralogy and Reactivity of Belite-Sulfoaluminate Clinkers

This study investigated the influence of different cooling regimes on the microstructure and consequent reactivity of belite-sulfoaluminate clinkers. The cement clinkers were synthesized by incorporating secondary raw materials, such as titanogypsum and bottom ash, to the natural raw materials. Clinker phases were determined by Rietveld quantitative phase analysis, while the distribution morphology and the incorporation of substitute ions in the phases were characterized by scanning electron microscopy using energy-dispersive X-ray spectroscopy (SEM/EDS). Clinker reactivity was studied using isothermal calorimetry and was additionally investigated through compressive strength, which was determined for the cement prepared from the synthesized clinkers. X-ray diffraction analysis showed that, as well as the three main phases (belite, calcium sulfoaluminate, and ferrite), the clinkers contained additional minor phases (mayenite, gehlenite, arkanite, periclase, and perovskite), the ratios of which varied according to the cooling regime utilized. Microscopic observations indicated that the cooling regime also influenced the crystal size and morphology of the main phases, which consequently affected clinker reactivity. Furthermore, a smaller amount of substitute elements was incorporated in the main phases when cooling was slowed. Results showed that, in comparison to clinkers cooled at slower rates, air quenched clinkers reacted faster and exhibited a higher compressive strength at 7 days.