International Consensus Statement on Rhinology and Allergy: Rhinosinusitis

Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document. Methods: ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided. Conclusion: This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS

Promotion effect of polymers and surfactants on hydrate formation rate

The promotion effect of two polymers and three surfactants on methane hydrate formation was investigated in a high-pressure system. For all of the tested chemicals, 1 wt % aqueous solutions were prepared and methane hydrate was formed in those media to detect their effect on hydrate formation rate. It was determined that Igepal-520 is the most effective promoter on methane hydrate formation rate with respect to a reference test carried out by using only pure water

PEO - A new hydrate inhibitor polymer

The hydrate inhibition potential of four different polymers has been tested in a high-pressure apparatus at high pressures and low temperatures. Aqueous polymer solutions were prepared at 1 wt % concentration. Methane (99.5% purity) was used as hydrate former gas. Hydrate formation rates of the tests were calculated to decide the best inhibitors. A known hydrate inhibitor, poly(N-vinylpyrrolidone) (PVP) and a water-soluble thermoplastic polymer TEO) were determined the best kinetic inhibitors among them

On the dissociation of natural gas hydrates from surfactant solutions

Natural gas hydrates from different types and concentrations of surfactant solutions were produced and dissociated in a high-pressure cell. The Clausius-Clapeyron equation was utilized to derive the enthalpy related to the phase transition of the gas component from dissociation data. The results indicated that the phase change enthalpy of the nonionic surfactant solution hydrate is higher compared to that of pure-water and anionic surfactant solution hydrates. Experimental results also show that surfactants do not influence the thermodynamic dissociation point

Surfactants as hydrate promoters?

Natural gas hydrates from different types and concentrations of surfactant solutions were produced in a high-pressure cell. An anionic, a cationic, and a nonionic surfactant were used to prepare different concentration of surfactant solutions from deionized water. Although the thermodynamics of hydrate formation from a gas mixture is not affected with the existence of surfactants in the environment, there is an appreciable effect of type and concentration of surfactant on hydrate formation rate. The hydrate formation rate is increased with the use of anionic surfactant for all concentrations tested. Hydrate formation rate is also increased at low concentrations of cationic surfactant. The effect of nonionic surfactant is less pronounced compared to anionic and cationic ones

Effect of an anionic surfactant on different type of hydrate structures

In this study, methane and gas mixture (including 88.17% propane) hydrates were produced from the anionic surfactant solutions of 0.00, 0.01 and 0.05 wt.% to investigate the effect of surfactant on the hydrate formation rate. Hydrate formation rate increases (promotion effect) with surfactant concentration, but the extent of the surfactant effect is closely related with the type of hydrate structure. The increase in the hydrate formation rate of sII type structure is relatively small compared to that obtained with structure sI

Spontaneous imbibition in low permeability carbonates

Spontaneous imbibition is important in oil recovery from fractured and low permeability tight gas reservoirs. Gas-water spontaneous imbibition experiments were conducted using low permeability heterogeneous limestone core plugs. The interfacial tension was changed by adding differing amounts of alcohol to water. It was observed that the true residual saturation of gas is very small for all cases. A much larger pseudo-residual saturation was achieved early in the imbibition stage but gas continued to be produced at extremely low rates until the true saturation was reached. The gas-water spontaneous imbibition performance was modeled using a mathematical model where the porous medium is represented as a bundle of equal but tortuous capillary tubes. Input data for this model was obtained from serial thin sections using a state of the art image processing system and a computerized microscope. The gaps between the thin sections were constructed using geostatistical techniques. It was observed that the model successfully explained the imbibition process in samples where pores with varying circularity were present. Average number of pore throats meeting at one pore in the pore skeleton ( coordination number) was less than six for all cases

Dependence of thermal stability of an engine lubricating oil on usage period

Mineral oil type lubricating oils have an important role in reducing engine wear. But after some period, depending on the oil quality, oil replacement is needed since the oil loses its properties. In this paper, an engine oil was tested in a 1300 cc engine car and the change of the thermal stability of the collected portions of oil at different usage periods were experimented by TG/DTG and DSC techniques. Results show that, as usage period increases lubricating oil contains more of the light components that distill at low temperatures. The increase in tine peak maximum temperature, T-max, of the DTG, as usage period increases, proposes that the molecular mass of the oil increase, which presumably changes the viscosity characteristics. Moreover as the usage period increases some residue type components, which only can be destroyed at very high temperatures, are produced in oil phase