Flow over blunt bodies with spikes and cavities

The influence of the shape of bodies of revolution with complicated generating lines on the coefficient of drag is investigated by the method of large particles.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 37, No. 4, pp. 712–716, October, 1979.     

Characteristics of spectrum registration of condensed medium by the method of nuclear-magnetic resonance in a weak field

The characteristics of signal registration of nuclear-magnetic resonance in a weak magnetic field from a small volume of an investigated medium have been considered. The consideration of the characteristics revealed in a new developed design of a magnetic system for a compact nuclear-magnetic spectrometer, and also in the NMR-signal registration method allows significant extension of the possibility to use the phenomenon of nuclear-magnetic resonance for the study of condensed medium in an express mode. The experimental results of different media studies have been presented.     

Graphene-based biosensors

Results of developing and testing graphene-based sensors capable of detecting protein molecules are presented. The biosensor operation was checked using an immunochemical system comprising fluorescein dye and monoclonal antifluorescein antibodies. The sensor detects fluorescein concentration on a level of 1–10 ng/mL and bovine serum albumin–fluorescein conjugate on a level of 1–5 ng/mL. The proposed device has good prospects for use for early diagnostics of various diseases.     

Small atomic clusters on graphene: A model approach

Analytical expressions for the density of states for a dimer and two types of a trimer (a string and a triangle) are obtained using the M-model. All of the features of the adatoms that comprise the studied small clusters are shown to be defined by the fundamental properties of density of states of the graphene base.     

Vibration of an atom absorbed on single-layer graphene: Account of electron-phonon interaction

Using simple models of the electron-phonon adatom-substrate coupling and the density of electron states for graphene (the M-model), the possibility of the coexistence of electron states of an adatom with different occupation numbers is analyzed. Estimations show that this situation is most probable for the adsorption of alkali metals on graphene.     

Double-cross epitaxial overgrowth of nonpolar gallium nitride layers

Epitaxial gallium nitride (GaN) structures have been manufactured by the lateral overgrowth technology, whereby GaN epilayers are grown in stripe windows on a partly masked initial GaN layer. It is established that in addition to the traditional orientation of stripes across the c axis, the process is also possible for the stripes oriented at 45° relative to this axis. In this case, two lateral overgrowth processes in mutually perpendicular directions can be performed, which would significantly reduce the relative area of imperfect material formed over windows in the mask.     

Local search for load balancing problems for servers with large dimension

We consider a new load balancing model that arises in the processing of user requests for files located on a given set of servers. The optimization criterion is the total excess of actual load over the limit load. In order to redistribute the load and minimize the criterion, files can be moved between the servers. We show that if there are no other constraints related to the stage of moving the files, then this problem is equivalent to a problem previously considered in literature. For this special case of this problem, we propose a stochastic local search scheme that combines a special procedure for fast querying of the neighborhoods and a procedure of non-aggravating modification of intermediate solutions. Results of numerical experiments show that the proposed approach is able to find high-quality solutions for instances of large dimension under tight time constraints.     

Investigation of the transition layer in 3C-SiC/6H-SiC heterostructures

Transmission electron microscopy and the cathodoluminescence method are used to study the transition region in 3C-SiC/6H-SiC heterostructures. It is shown that this region is, as a rule, constituted by alternating 3C-SiC and 6H-SiC layers with the possible inclusion of other silicon carbide polytypes. An assumption is made that this structure of the transition region can be explained in terms of the model of spinodal decomposition.