Use of Periclase-Carbon Refractories for the Lining of 385-Ton Steel-Teeming Ladles for a Furnace-Ladle Unit Installed in an Oxygen-Converter Shop at the Magnitogorskii Metal-And-Steel Works Joint-Stock Co.

Refractories and Industrial Ceramics -     

Induction plasma synthesis of fullerenes and nanotubes using carbon black–nickel particles

The existence of fullerenes (as allotropes of carbon) was established in the mid-1980s and during the last 15–18 years, systematic efforts have been devoted to improve the methods of their synthesis, including plasma-based system methods. The work presented here is focused on the investigation of fullerenes synthesis, using a radio frequency plasma reactor. The main objectives were to explore the use of induction plasma technology for the synthesis in-continuo of carbon fullerenes and to predict their formation conditions through conduct of theoretical studies. Thus, a thermodynamic study was carried out to predict the equilibrium composition of fullerenes produced at several combinations of operating conditions. Additionally, a statistical factorial design experiment, employing four factors at two levels, was also developed, in order to study the influence of the system’s operating parameters on the eventual C₆₀ fullerene yield. The results obtained showed that the reactor pressure, the electrical power and the raw material feed rates all have an important effect on the synthesis of fullerenes. The highest C₆₀ concentration in the products was found to be about 7.7 wt.%. Various other carbon nanostructures, such as nanotubes and nano-onions, were also successfully produced.     

Felt polishers with fibers perpendicular to the glass surface

Glass and Ceramics -     

Pro- und Antioxydantien auf dem Fettgebiet XVII: Fette und Fettstoffwechsel der Winterschläfer, 1. Mitteilung: Der Siebenschläfer (Glis glis L.)

Pro- and Antioxidants in the Field of Fats XVII: Fats and Fat-metabolism of Hibernating Animals I. The Seven Sleepers. (Glis glis L.) After a short review of the literature about hibernation, the analysis of the lipids of the seven sleepers (Glis glis L.) is given. The problem, whether the yellow lipochrome results from the autoxidation of polyenoic fatty acids because of the decrease in biological antioxidants, especially vitamin E, could not be completely explained. The brown tissue, the socalled “sleep gland” contains substances which are insoluble in fat solvents and probably formed by the reaction of polyenes with proteins or by the autoxidation of lipoproteins which contain them.     

Strain-induced crystallization,Part IV: Induction time analysis

The empirical equation, 1/t_i = Ae^Ei/RT, which expresses the exponential dependence of the reciprocal of crystallization induction time, t_i, has been analyzed and shown to be equivalent to the nucleation rate equations derived earlier in Part III (1). Consequently we have used the t_i measurements obtained earlier by Krueger and Yeh to calculate not only the nucleation rate enhancements but also the melting point elevations, the relative crystal thickness changes and molecular coil extension ratios of shear-crystallization polyethylene. It is shown that polyethylene when crystallized between 129 and 131°C at shear rates between 1.56 and 9.70 sec^?1 can have melting point increases of 4.2 to 7.2°C and crystal thickness decreases of 20 to 25 percent, when compared to those crystallized at 130°C in the quiescent state. The predicted “coil” extension in the melt just prior to shear-induced crystallization ranges between 21 and 36 percent. The results of these analyses as well as those on nucleation rates of polyethylene oxide are discussed in detail.     

Composition and Properties of Biodegradable Materials

The important possibility of fabricating biodegradable materials by incorporating different bio- and photodegradable additives in the polymer is demonstrated. Changes were found in the structure and properties of degradable materials during exposure to soil microorganisms, air, and UV radiation for different times. The results obtained can serve as the basis for a more in-depth investigation of the mechanism of degradation of PCM.     

Mechanism of refractory wear in the reaction shaft of furnaces for melting of raw material in the suspended state

Conclusions The mechanism of failure of chrome-magnesite refractories under conditions of autogenous melting of sulfide ore was studied.On the basis of an analysis of the thermal operation of the lining taking into consideration the closeness of domestic refractories in thermophysical properties to Radex CN refractories, lining of the reaction shaft with domestic refractories was recommended.Translated from Ogneupory, No. 5, pp. 49–52, May, 1986.     

Use of mesoporous SBA-15 for nanostructuring titania for photocatalytic applications

SBA15–TiO₂ samples prepared by introducing titanium with a grafting method and having TiO₂ loadings below 15 wt.% have been characterized by XRF, XRD, IR, porosimetry, SEM, HRTEM, and UV–Visible diffuse reflectance. Differently from the samples reported in the literature characterized by a high TiO₂ loading, no evidences have been found for the presence of titania particles inside or outside the mesopores of SBA-15. Three different titanium species were instead evidenced to be present. The first two derive from the reaction of titanium with silanol groups in the corona area of inner SBA-15 walls leading to the formation of either TiO₄ tetrahedral sites (by reaction by hydroxyl nests of surface defect sites) and/or pseudo-octahedral surface sites anchored by two (or more) Si or Ti ions through bridging oxygens. The third species derives from the reaction of titanium in the regions with high sylanol density, e.g. in the micropores located in the corona of SBA-15 channels, leading to the formation of TiO₂-like nanoareas (probably Si-doped) with dimensions of around 1–2 nm maximum. The potential interest of these materials as photocatalysts, for the presence of a TiO₂-like nanoareas highly accessible by reactants, is discussed.