Efficient Data Storage in Large Nanoarrays

We explore the storage of data in very large crossbars with dimensions measured in nanometers (nanoarrays) when h-hot addressing is used to bridge the nano/micro gap. In h-hot addressing h of b micro-level wires are used to address a single nanowire. Proposed nanotechnologies allow subarrays of 1s (stores) or 0s (restores) to be written. When stores and restores are used, we show exponential reductions in programming time for prototypical problems over stores alone. Under both operations, it is NP-hard to find optimal array programs. Under stores alone it is NP-hard to find good approximations to this problem, a question that is open when restores are allowed. Because of the difficulty of programming multiple rows at once, we explore the programming of single rows under h-hot addressing. We also identify conditions under which good approximations to these problems exist.     

Supporting Multiple Consistency Models within a Mobility Enabled File System Using a Component Based Framework

Most existing Distributed File Systems (DFSs) implement a single consistency model to maintain one-copy equivalence. The functionality of that consistency model is based on a balance between environmental constraints and the targeted level of consistency. Such systems efficiently maintain consistency while the environmental capabilities remain constant, e.g., presuming uninterrupted connectivity. However, when these characteristics change, the inflexible nature of a single consistency model results in its inability to maintain an expected balance between consistency and constraints. This illustrated with existing implementations of DFSs. GLOMAR is a DFS middleware layer that allows application developers to map their specific consistency models to environmental constraints. As a result, multiple consistency models can be created, with each scoped for a particular application and environmental scenario. This paper outlines important aspects of GLOMAR, detailing its implementation and outlining a number of consistency models.     

Self-Organizing Cyclolinear Organosilicon Polymers in Bulk and on the Surface of Water ?

Cyclolinear organocarbosiloxane polymers with varying content and location of (CH₂)_n groups in the monomer unit were synthesized by reactions of heterofunctional polycondensation and polyaddition of difunctional organocyclosiloxanes and organocyclocarbosiloxanes. Their bulk properties were studied by differential scanning calorimetry and X-ray structural analysis. It was shown that on introduction of CH₂ groups into the methylcyclohexasiloxane unit, the polymer retains the ability to self-organize with formation of a mesomorphic state in a wide temperature range, while on introduction of (CH₂)₂ fragments in a cyclotetrasiloxane unit or in a bridge connecting two methylcyclotetra(hexa)siloxane units it does not. Comparison of the X-ray data of dihydroxy derivatives of decamethylcyclohexasiloxane and decamethyl-5-carbocyclohexasiloxane with packing of cyclolinear organosilicon polymers in bulk shows that the polymer inherits the layered type of crystalline structure typical for monomers. Langmuir films of cyclolinear polymethylcarbosiloxanes with different design of monomer units were studied as well. It was revealed that all polymers form monomolecular films at the air/water interface, excluding those having longer hydrophobic fragment than hydrophilic ones. The ability to form multilayers depends on the surroundings of Si atom in the bridge between the cycles.     

Flame-sound interaction in tubes with nonslip walls

Flame interaction with sound is studied for a premixed flame propagating to the closed end of a tube with nonslip walls. The flow geometry is similar to that in the classical Searby experiments on flame-acoustic interaction [Combust. Sci. Technol. 81 (1992) 221]. The problem is solved by direct numerical simulations of the combustion equations. The flame-sound interaction strongly influences oscillations of the flame front. Particularly, sound noticeably increases the oscillation amplitude in comparison with that in an open tube with nonreflecting boundary conditions at the ends studied previously. Oscillations become especially strong in the second part of the tube, where flame pulsations are in resonance with the acoustic wave. Parameters of the flame oscillations are investigated for different values of the tube width and length. It is demonstrated that the oscillations are stronger in wider tubes, though the investigated tube width is limited by the computational facilities. In sufficiently wide tubes, violent folding of a flame front is observed because of the flame-acoustic resonance. By increasing the Lewis number, one also increases the oscillation amplitude.     

Manipulating of Resonances in Conductance of an Electron Waveguide with Anti-Dots

A new scenario of quantum interference in open systems when a decaying (quasi-bound) state can interfere with the continuum is investigated. The resonant perturbation theory and numerical methods are applied to treat a scattering problem in an electron waveguide. Specifically, we use the Kapura and Peierls (KP) approach to extract resonances. In the waveguide with two and three anti-dots, we observe an interesting phenomenon: the interference between one subband of the quasi-bound states and background second subband, and the interference of resonant group states of different subbands. Our results show that the zero of Fano resonance, arising from the interference between the quasi-bound states and the continuum, is generally placed in the complex plane.     

Saving the Aral sea

The wrong strategy of economic development pursuing the goal of one‐sided expansion of water‐consuming cotton and rice monoculture has led to heavy withdrawals of river flow for irrigation. Consequently, as a result of diminishing inflow, the Aral Sea began to shrink in volume and area and is now on the verge of total collapse. The tragedy can be averted if recommendations of the recently elaborated concept for conservation and restoration of the sea are realized without any delay. This could save the sea as a productive water body and normalize the socio‐economic, ecological and medical situation in the Aral region.     

Reagentless biosensor based on glucose oxidase wired by the mediator freely diffusing in enzyme containing membrane

Wiring glucose oxidase in the membrane with an immobilized mediator is possible due to the diffusion ability of the latter, if the enzyme containing membrane is formed according to the proposed protocol, including exposing proteins to water-organic mixtures with the high content of organic solvent. In the course of the study, the new glucose oxidase mediator, unsubstituted phenothiazine, was discovered. The diffusion coefficient of the mediator in the resulting membrane is independent of the presence of enzyme. The cyclic voltammograms of the enzyme electrode after appearance of the only glucose in solution obtain a well-defined catalytic shape, which is normally observed for both the enzyme and the mediator in solution. Analytical performances of the resulting biosensor are comparable to the advanced second generation ones, which, however, require covalent linking of the mediator either to the membrane forming polymer or to the enzyme. Even without such covalent linking, the reported biosensor is characterized by an appropriate long-term operational stability allowing reagentless sensing.     

Polymer systems in geothermal applications

The feasibility of using a copolymer composed of styrene, acrylonitrile, and acrylamide or methacrylamide in the formation of a high-strength thermally and chemically stable polymer concrete for use in geothermal environments has been demonstrated. Specimens produced with the copolymer in conjunction with an aggregate containing sand and portland cement had compressive strengths in the range of 25,000 to 30,000 psi at 20°C and were thermally stable up to ～240°C. A study of the effect of monomer concentration on the properties of the polymer concrete indicated that the optimum concentration is in the range of 12 to 13 wt. %. Increased monomer concentrations lead to a nonuniform polymer distribution within the composite, resulting in a deterioration of the properties. The optimum properties are obtained when the monomer is used in conjunction with an aggregate containing 70 to 80 wt. % silica sand and 20 to 30 wt. % portland cement. The results from laboratory and field evaluations in progress indicate that the materials can be used for pipe or as protective liners on pipe and vessels in electric generating and direct utilization geothermal processes.