Dielectric spectroscopy techniques as quality control tool: a feasibility study - [feature article]

In this article, the feasibility of using time- and frequency-domain dielectric spectroscopy measurements to monitor the condition of oil-impregnated paper (OIP) condenser bushings is discussed.     

Surface modification of commercial carbon black by silane coupling agents for improving dispersibility in rubber compounds

The dispersion of a filler in a rubber matrix is a crucial parameter affecting the mechanical and dynamical properties of a rubber compound. It is the current issue of the rubber compounding industry because, most fillers are categorized as a mineral, while the rubber is an organic material. The surface modification of the filler has been accepted as an effective technique for the improvement of the abovementioned parameter. First, the surface premodification of commercial carbon black with a grade of N660 (CB) was implemented by four different oxidation methods. After that, among of used methods, the oxidation method using citric acid was selected to produce modified carbon black (CB-Oxi) for further treatment. Subsequently, the coupling agent, Bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT) was functionalized on the surface of CB-Oxi to produce modified-CB-Oxi. Also, for comparison purposes, the TESPT functionalization was accomplished on untreated CB to form modified-CB. The FTIR spectra of CB-Oxi showed using the premodification method introduced the hydroxyl and carboxyl groups on the surface of CB. The correspondent spectra for modified-CB-Oxi confirmed the existence of silane groups on the surface of the carbon black. However, the mentioned silane groups were not observed on the surface of modified-CB. The findings were strengthened by several characteristic techniques including, FESEM, XRD, EDS, CHNS elemental analysis, and RAMAN spectra. The FESEM graphs and elemental mapping showed homogeneous dispersion and uniform distribution of sulfur and silicon elements on the modified-CB-Oxi surface. According to RAMAN spectra, the disturbance in the structure of carbon black graphite was reduced after surface modification. modified-CB-Oxi is proposed as a potential substitute filler for current commercial carbon black in rubber compounding.     

How Can We Improve Vaccination Response in Old People? Part I: Targeting Immunosenescence of Innate Immunity Cells

Vaccination, being able to prevent millions of cases of infectious diseases around the world every year, is the most effective medical intervention ever introduced. However, immunosenescence makes vaccines less effective in providing protection to older people. Although most studies explain that this is mainly due to the immunosenescence of T and B cells, the immunosenescence of innate immunity can also be a significant contributing factor. Alterations in function, number, subset, and distribution of blood neutrophils, monocytes, and natural killer and dendritic cells are detected in aging, thus potentially reducing the efficacy of vaccines in older individuals. In this paper, we focus on the immunosenescence of the innate blood immune cells. We discuss possible strategies to counteract the immunosenescence of innate immunity in order to improve the response to vaccination. In particular, we focus on advances in understanding the role and the development of new adjuvants, such as TLR agonists, considered a promising strategy to increase vaccination efficiency in older individuals.     

Stoffaustausch zwischen flüssigem Eisen und Schlacke beim Sprühraffinationsverfahren

Erläuterung des Sprühraffinationsverfahrens, bei dem eine Schmelze mit inertem Gas verdüst wird und die entstehenden Metalltropfen durch eine Raffinationsschlacke fallen. Erörterung der Gesetzmäßigkeiten für die Stoffaustauschvorgänge zwischen Metalltropfen und Schlacke. Bestimmung der mittleren Tropfengröße beim Versprühen von kohlenstoffgesättigtem Roheisen. Untersuchung der Wirkung der Sprühraffination am Beispiel der Entschwefelung des Roheisens mit Schlacken des Systems CaO–CaF₂–Al₂O₃ bei 1600 °C. Ermittlung des Stoffübergangskoeffizienten des Schwefels für den umgekehrt transitorischen Phasenkontakt und Vergleich mit Werten bei anderen Techniken des Phasenkontaktes Metall-Schlacke.     

Optimal power generation from low concentration coal bed methane in Iran

Development of a model for optimal power generation from the thermal oxidation of a low concentration coal bed mine has been considered as the main objective of this investigation. The model has been applied to identify the optimal thermodynamic characteristics of the power generation system through using a mixture with 1.6% methane concentration in a recuperative lean-burn gas turbine and coupling a gas engine to the system for more power generation from the remaining coal bed methane. The implementation of the model based on the real site condition would lead to the generation of 6.97 MW electricity in Tabas coal mine of Iran.     

Wind-tunnel investigation of icing of an inclined cylinder

The effects of varying the angle of wind velocity and axis of a cylindrical icing object around all of the three mutually perpendicular axes are studied experimentally. The mass, shape and profile of ice accretion obtained in a horizontal icing wind tunnel are investigated as functions of cylinder inclination. The icing object is exposed to two types of aerosol cloud, which are created by different procedures: (i) injecting small droplets horizontally into cold air flow, (ii) injecting vertically falling large droplets into cold air flow; so that the resulting conditions simulate in-cloud icing and freezing rain, respectively. Observations reveal the effects of varying each angle on the mass, shape and profile of ice accreted under both conditions.