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.     

Study of fullerenes via their symmetry groups

In this paper, we compute the automorphism group of some infinite classes of fullerene graphs and then we compute their symmetric Szeged index which is a new topological index based on the automorphism group.     

Efficient batch-mode mixing and flow patterns in a microfluidic centrifugal platform: a numerical and experimental study

During recent years centrifugal-based microfluidic devices known as Lab-on-a-CD have attracted a lot of attentions. Applications of these CD-based platforms are ubiquitous in numerous biological analyses and chemical syntheses. Mixing of different species in microscale is one of the essential operations in biochemical applications where this seemingly simple task remains a major obstruction. Application of centrifugal force, however, may significantly improve the flow agitation and mixing, especially when it is combined with the Coriolis force which acts perpendicular to centrifugal force. In this study, mixing process in minichambers located on a rotating platform under a periodic acceleration and deceleration angular velocity profile is investigated both numerically and experimentally. We have incorporated various arrangements of obstacles and baffles, which are usually used in stationary mixers, within a batch-mode rotating mixing chamber. Subsequently, the effect of these obstacles on flow field and mixing process has been studied, and among these arrangements four cases have been selected for further experimental analysis. Experimental studies have been performed on a multi-layer CD platform fabricated in polycarbonate plates, and subsequently mixing has been investigated in these minichambers. The quantitative mixing data were obtained after a set of image analyses on the captured images of mixing chamber during the process and the results were compared with the simulation. The results indicate a good resemblance between the two studies both qualitatively and quantitatively. Furthermore, it has been shown that the application of obstacles and baffles together in chamber results in reducing the mixing time more than 50 % as compared to a chamber without any obstacle and/or baffle configuration. Obtaining mixing times less than 10 s in both studies, makes these CD-based platforms an appropriate device for many applications in which a cost-effective device as well as low mixing time is required.

     

Structural and electronic properties of C and BN nanotubes based on periodic fullerenes: A density functional theory study

The structural and electronic properties of C and BN nanotubes based on periodic fullerenes were studied using density functional theory. It was shown that these tubular structures are stable. The electronic band structures and density of states indicated that the C nanotubes based on periodic fullerenes are metals. The energy band gap was appeared by substitution of C atoms with B and N atoms. The BN nanotubes based on periodic fullerenes show semiconducting properties. Our results suggest that the nanotubes based on periodic fullerenes can be used to design of nanoelectronic devices.     

An algebraic study of non classical fullerenes

The Wiener index is the oldest topological index based on the sum of distances between any pair of vertices in given graph. An algebraic approach for generalizing the Wiener index was proposed by Graova? and Pisanski for the first time. In this paper, we compute the modified Wiener index and then the differences between Wiener and modified Wiener indices of an infinite class of non-classical fullerenes.     

A biological multiplexer,designs, and simulations

Biological circuits can be used in synthetic biology to perform logical functions similar to those observed in electronic circuits. These circuits are applied as a method to define cellular functions in useful ways. The purpose of this field of research is to design and simulate systems which can combine VLSI technology and biological circuits. In this regard, five different architectures (AND–OR, AND–NOR–OR–AND Full-NAND, and Full-NOR) of a new biomultiplexer have been designed and simulated. The results of these architectures are compared in terms of delay as well as the number of promoters and genes. The two-level architectures AND–OR, AND–NOR, and OR–AND, in addition to the greater number of genes and promoters, have also a longer execution time than the designs with two universal NAND or NOR gates. In Full-NAND design, the execution time is reduced by lowering the number of genes and the number of promoters. Finally, Full-NOR design offers the shortest execution time of 0.612 s, while reducing promoters by 64% and the number of genes by 50%, compared to other proposed architectures.