Deterministic collision free communication despite continuous motion

We present a deterministic solution for nodes in a mobile wireless ad hoc network to communicate reliably and maintain local neighborhood information. The nodes are located on a two-dimensional plane and may be in continuous motion. In our solution we tile the plane with hexagons. Each hexagon is assigned a color from a finite set of colors. Two hexagons of the same color are located sufficiently far apart so that nodes in these two hexagons cannot interfere with each other’s broadcasts. Based on this partitioning we develop a periodic deterministic schedule for mobile nodes to broadcast. This schedule guarantees collision avoidance. Broadcast slots are tied to geographic locations instead of nodes and the schedule for a node changes dynamically as it moves from tile to tile. The schedule allows nodes to maintain information about their local neighborhood. This information in turn is used to keep the schedule collision-free. We demonstrate the correctness of our algorithm, and discuss how the periodic schedule can be adapted for different scenarios. The periodic schedule, however, does not address the problem of initial neighbor discovery at start-up. We give a separate algorithm for this problem of initially discovering nodes present within communication range at start-up.     

Silk proteins for biomedical applications: Bioengineering perspectives

Biomaterials of either natural or synthetic origin are used to fabricate implantable devices, as carriers for bioactive molecules or as substrates to facilitate tissue regeneration. For the design of medical devices it is fundamental to use materials characterized by non-immunogenicity, biocompatibility, slow and/or controllable biodegradability, non-toxicity, and structural integrity. The success of biomaterial-derived biodevices tends to be based on the biomimetic architecture of the materials. Recently, proteins from natural precursors that are essentially structural and functional polymers, have gained popularity as biomaterials. The silks produced by silkworms or spiders are of particular interest as versatile protein polymers. These form the basis for diverse biomedical applications that exploit their unique biochemical nature, biocompatibility and high mechanical strength. This review discusses and summarizes the latest advances in the engineering of silk-based biomaterials, focusing specifically on the fabrication of diverse bio-mimetic structures such as films, hydrogels, scaffolds, nanofibers and nanoparticles; their functionalization and potential for biomedical applications.     

AC Potential-Dependent Concentration Variation and Domain Wall Pinning in Co1−x Zn x (x=0.4−0.5) Nanorods

The Co_1?x Zn _x (x=0.4?0.5) nanorods were synthesized via an AC electrochemical deposition method into anodized aluminum oxide (AAO) templates at different voltages ranging from 10 to 18 V, and nanorods of varying concentrations of Co and Zn were obtained. The characterization tools were used to examine different aspects of nanorods, e.g., shape, size, morphology, chemical composition, and magnetic behavior. Scanning electron microscope (SEM) images show that CoZn nanorods have length L=1μm and diameter d=50 nm. The grain size was calculated to be 25.4 nm using an X-ray diffraction (XRD) technique. The XRD also shows some other phases of ZnCoO. The M?H loops measured by a vibrating sample magnetometer (VSM) at room temperature show pure ferromagnetic behavior at all AC potentials. The nanorods show magnetic isotropic behavior due to strong magnetic interactions and presence of random nanorods. The potential-dependent coercivity H _c and saturation magnetization M _s show a non-linear curve which is explained on the basis of magnetic islands and domain wall pinning. This study is useful to tune the magnetic properties of nanorods by a simple and low-cost technique.     

Controlled nanostructuring of multiphase core-shell nanowires by a template-assisted electrodeposition approach

Multiphase core-shell nanowires have been fabricated by controlling the ion transport processes of the microfluids in the nanochannels of the template. Both forced convection and pulsed potential induced migration can be applied to tune the morphologies of the nanostructures obtained by manipulating the ion transport during electrodeposition. The morphology and content of the core-shell structure were studied by field emission scanning electron microscope (FESEM) analysis, transmission electron microscope (TEM) analysis and energy dispersive spectrometry (EDS), respectively. The magnetic properties were analyzed by vibrating sample magnetometer (VSM) analysis. A magnetically hard core and soft shell constitutes the multiphase composite nanostructure. The unique magnetic hysteresis curve indicates the decoupled magnetic reversal processes of the two components. Our work provides deeper insights into the formation mechanisms of a new core-shell nanostructure, which may have potential applications in novel spintronics devices.     

Fabrication of silver monoliths using Brij 52 surfactant and TiO2 nanoparticles and their applications to reduce Fast Sulphon Black F dye and sensor against Pb2+

Journal of Materials Science: Materials in Electronics - Silver monoliths were prepared using Brij 52 as surfactant with and without dextran and reinforcing agents TiO2NPs by modified sol–gel...     

Multiplexing Superconducting Qubit Circuit for Single Microwave Photon Generation

We report on a device that integrates eight superconducting transmon qubits in \(\lambda /4\) superconducting coplanar waveguide resonators fed from a common feedline. Using this multiplexing architecture, each resonator and qubit can be addressed individually, thus reducing the required hardware resources and allowing their individual characterisation by spectroscopic methods. The measured device parameters agree with the designed values, and the resonators and qubits exhibit excellent coherence properties and strong coupling, with the qubit relaxation rate dominated by the Purcell effect when brought in resonance with the resonator. Our analysis shows that the circuit is suitable for generation of single microwave photons on demand with an efficiency exceeding 80%.     

A Service Level Agreement Aware Online Algorithm for Virtual Machine Migration

The demand for cloud computing has increased manifold in the recent past. More specifically, on-demand computing has seen a rapid rise as organizations rely mostly on cloud service providers for their day-to-day computing needs. The cloud service provider fulfills different user requirements using virtualization - where a single physical machine can host multiple Virtual Machines. Each virtual machine potentially represents a different user environment such as operating system, programming environment, and applications. However, these cloud services use a large amount of electrical energy and produce greenhouse gases. To reduce the electricity cost and greenhouse gases, energy efficient algorithms must be designed. One specific area where energy efficient algorithms are required is virtual machine consolidation. With virtual machine consolidation, the objective is to utilize the minimum possible number of hosts to accommodate the required virtual machines, keeping in mind the service level agreement requirements. This research work formulates the virtual machine migration as an online problem and develops optimal offline and online algorithms for the single host virtual machine migration problem under a service level agreement constraint for an over-utilized host. The online algorithm is analyzed using a competitive analysis approach. In addition, an experimental analysis of the proposed algorithm on real-world data is conducted to showcase the improved performance of the proposed algorithm against the benchmark algorithms. Our proposed online algorithm consumed 25% less energy and performed 43% fewer migrations than the benchmark algorithms.     

Carburization of Si microwires by chemical vapour deposition

We report the elaboration of silicon carbide (SiC) nanostructures thanks to the carburization of silicon microwires (MWs) under methane at high temperature. The produced SiC nanostructures display a tubular shape and are polycrystalline. The as-prepared silicon carbide microtubes (MTs) were characterized and studied by scanning electron microscopy (SEM), dual focused ion beam-scanning electron microscope (FIB-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The formation of microtubes can be explained by the out-diffusion of Si through the SiC during the carburization process.     

Patterned assembly of genetically modified viral nanotemplates via nucleic acid hybridization

The patterning of nanoparticles represents a significant obstacle in the assembly of nanoscale materials and devices. In this report, cysteine residues were genetically engineered onto the virion surface of tobacco mosaic virus (TMV), providing attachment sites for fluorescent markers. To pattern these viruses, labeled virions were partially disassembled to expose 5' end RNA sequences and hybridized to virus-specific probe DNA linked to electrodeposited chitosan. Electron microscopy and RNAase treatments confirmed the patterned assembly of the virus templates onto the chitosan surface. These findings demonstrate that TMV nanotemplates can be dimensionally assembled via nucleic acid hybridization.