Wind Feedback Mediated by Sea Ice in the Nordic Seas

Air–sea interactions play a critical role in the climate system. This study investigates wind-induced changes in the ocean surface temperature and sea ice cover feeding back onto the atmospheric circulation. This interaction was modeled in the Nordic seas, using a partial coupling method to constrain the ocean with prescribed wind forcing in an otherwise fully coupled Earth system model. This enabled the evaluation of not only the direct oceanic, but also the indirect atmospheric response to idealized forcing scenarios of perturbed winds over the Nordic seas. The results show that an anticyclonic wind anomaly forcing leads to significant surface cooling in the Greenland Sea mostly due to anomalous drift of sea ice. During winter, the cooling reduces the net surface heat flux to the atmosphere and increases sea level pressure. The pressure gradients result in anomalous geostrophic southerly winds, which locally are comparable both in direction and in velocity to the prescribed forcing anomalies, suggesting a positive feedback.

Application of Sulfated Tin (IV) Oxide Solid Superacid Catalyst to Partial Coupling Reaction of α-Pinene to Produce Less Viscous High-Density Fuel

Brønsted acid-catalyzed reactions of α-pinene have been studied because of their ability to produce various types of fragrance molecules. Beyond this application, dimeric hydrocarbon products produced from coupling reactions of α-pinene have been suggested as renewable high-density fuel molecules. In this context, this paper presents the application of a sulfated tin(IV) oxide catalyst for the partial coupling reaction of α-pinene from turpentine. Brønsted acid sites inherent in this solid superacid catalyst calcined at 550 °C successfully catalyzed the reaction, giving the largest yield of dimeric products (49.6%) at 120 °C over a reaction time of 4 h. Given that the low-temperature viscosity of the mentioned dimeric products is too high for their use as a fuel in transportation engines, lowering the viscosity is an important avenue of study. Therefore, our partial coupling reaction of α-pinene provides a possible solution as a considerable amount of the isomers of α-pinene still remained after the reaction, which reduces the low-temperature viscosity. On the basis of a comparison of the reaction products, a plausible mechanism for the reaction involving coinstantaneous isomerization and coupling reaction of α-pinene was elucidated.

INFLUENCE OF THE CEMENT COMPOSITION ON THE PROPERTIES OF REINFORCED CONCRETE STRUCTURES WORKING IN HIGH TEMPERATURE CONDITIONS

In the article the influence of binder hardening of concrete processes and changes in the phase composition of cement by heating to 1000 °С. It was established that the presence of active mineral adds in cement composite increases the strength of concrete at ordinary temperatures as well as when heated in a fire. Damage of structures, accompanied by loss of strength characteristics of concrete under the influence of high temperatures of the fire due to the decomposition of water-containing crystalline hydrates, which are formed when locked up with water. The analysis of the results of physical and mechanical investigations of portland cement with applications of meadow waste has shown that their loading allows to significantly increase the strength of this cement stone, due to the formation of an additional amount of sodium sulfate or potassium. Their influence as activators of hardening is most noticeable in the initial terms and gradually decreases with age of hardening. It has been shown that use in the composition of the binder of meadow-based additives and hydrosilics makes it possible to increase the strength of the cement stone by 1.5 times, which is essential for the development of effective composite binders on its basis for work in high temperatures. In this, the presence of fluoride aluminium in hydrosilic in a quantity of 3.3% by weight determines its plastisizing effect on cement. It has been experimentally stated that during the heating of concrete above 500°C, the destruction of hydrated components of cement stone with the destruction of structural bonds between individual particles with a significant decrease in strength characteristics. In this case, the use of applications provides a partial coupling of CaO in the process of solid phase reactions during heating. It is proved that the use of composite cement, as a binder, due to the presence of its composition of a meadow-based application - accelerates hardening and improves strength characteristics, hydrosilics - increases residual strength at a pressure of up to 1000°С by 2.4 MPa .