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Solid-state electronic transport (ETp) via the electron-transfer copper protein azurin (Az) was measured in Au/Az/Au junction configurations down to 4 K, the lowest temperature for solid-state protein-based junctions. Not only does lowering the temperature help when observing fine features of electronic transport, but it also limits possible electron transport mechanisms. Practically, wire-bonded devices-on-chip, carrying Az-based microscopic junctions, were measured in liquid He, minimizing temperature gradients across the samples. Much smaller junctions, in conducting-probe atomic force microscopy measurements, served, between room temperature and the protein's denaturation temperature (∼323 K), to check that conductance behavior is independent of device configuration or contact nature and thus is a property of the protein itself. Temperature-independent currents were observed from ∼320 to 4 K. The experimental results were fitted to a single-level Landauer model to extract effective energy barrier and electrode-molecule coupling strength values and to compare data sets. Our results strongly support that quantum tunneling, rather than hopping, dominates ETp via Az.

The present investigation is focused on the in-situ synthesis of Graphene oxide (GO)-ferrite nanoparticle hybrid framework by gel-combustion method followed by fabrication of homogeneous, structurally stable thin (~100–120 μm) hybrid-polyurethane coating on a metallic aluminum substrate and its application on the properties of broadband absorption over the microwave frequency region. Microstructure studies of hybrid materials illustrated that small sized ferrite nanoparticles (~17 nm) are grafted on and through the graphene layers, which forms a homogeneous coating thereby. The hybrid-nanocomposite coating demonstrated superior broadband absorption properties with absorptivity higher than 90% throughout a bandwidth of ~6 GHz, and moreover, it was found that with increased loading of GO in the nanocomposite, the bandwidth range of absorption frequency increases with enhanced absorptivity. The real part and imaginary part of the surface impedance values of the coating was obtained as 377 Ω and 0 Ω, respectively, which imply that the free-space impedance of the hybrid-nanocomposite coating is matching correctly. The nanocomposite coating showed ultra-high absorptivity over the frequency band of 8–12 GHz, which has numerous practical applications as radar absorbing materials (RAM), stealth technology, electromagnetic shielding, and radiated electromagnetic interference (EMI) management in onboard spacecraft and many more.

We report the in-situ synthesis of (M$g_{0.5} Zn_{0.5}$)$Fe_{2}O_{4}$-graphene oxide (MZF-GO) ferrite nanoparticle hybrid nanocomposite by auto-combustion technique followed by fabrication of homogeneous, structurally stable thin layer (-100-120 $\mu$m) of nanocomposite-polyurethane coating on metallic substrate (A1) and its application on the properties of broadband microwave absorption over the gigahertz (GHz) frequency range. Microstructure studies of nanocomposites depicted that small sized ferrite nanoparticles $(-24 \pm 6 nm)$ are grafted on and through the graphene layers, which forms a homogeneous coating. The nanocomposite-polymer coating demonstrated excellent broadband absorption properties with absorptivity of greater than 85%. The nanocomposite-polymer coating showed good absorptivity over the frequency band of 4-15 GHz, which has numerous practical applications as radar absorbing materials (RAM), stealth technology, electromagnetic shielding, and many more.

A rapid and controlled reduction method of graphene oxide (GO) along with their performances as broadband frequency absorbers is demonstrated in this report. The microwave-controlled rapid GO reduction technique was adopted to control the exfoliation, structural defects, and the localized electron concentrations while keeping the carbon network in graphene intact. The reduction technique is facile and scalable to produce gram-scale graphene with a controlled manner for preparing a sprayable, lightweight coating (coating thickness ~100–120 μm) throughout a large-area (~225 mm diagonal distances) substrate. The as-prepared coating was explored as active broadband frequency absorbing material in the 4–15 GHz frequency region. We obtained extraordinary absorption properties with an absorptivity average ~96% along with the successive broadening of the bandwidth of ~8.5 GHz throughout the absorption band. The retrieved real and imaginary parts of the surface impedance signify proper impedance matching with the free space; thereby providing high absorption at the aforementioned frequency band. The presence of residual oxygen-containing functional groups results in the differential ability to accumulate electrons, which generate the electric dipole under alternating electromagnetic field while electron hysteresis in these dipoles results in additional surface polarization, which effectively increases the microwave absorption potential of rGO compared to pristine GO.

The predominant use of wireless access networks is for media streaming applications, which are only gaining popularity as ever more devices become available for this purpose. However, current access networks treat all packets identically, and lack the agility to determine which clients are most in need of service at a given time. Software reconfigurability of networking devices has seen wide adoption, and this in turn implies that agile control policies can be now instantiated on access networks. The goal of this work is to design, develop and demonstrate QFlow, a learning approach to create a value chain from the application on one side, to algorithms operating over reconfigurable infrastructure on the other, so that applications are able to obtain necessary resources for optimal performance. Using YouTube video streaming as an example, we illustrate how QFlow is able to adaptively provide such resources and attain a high QoE for all clients at a wireless access point., Comment: Submitted to ToN in May, 2020

Electrons living in a two-dimensional world under a strong magnetic field - the so-called fractional quantum Hall effect (FQHE) - often manifest themselves as fractionally charged quasiparticles (anyons). Moreover, being under special conditions they are expected to be immune to the environment, thus may serve as building blocks for future quantum computers. Interference of such anyons is the very first step towards understanding their anyonic statistics. However, the complex edge-modes structure of the fractional quantum Hall states, combined with upstream neutral modes, have been suspected to prevent an observation of the much sought after interference of anyons. Here, we report of finding a direct correlation between the appearance of neutral modes and the gradual disappearance of interference in a Mach-Zehnder interferometer (MZI), as the bulk filling factor is lowered towards Landau filling {\nu}_B =1; followed by a complete interference quench at {\nu}_B=1. Specifically, the interference was found to start diminishing at {\nu}_B~1.5 with a growing upstream neutral mode, which was detected by a born upstream shot noise in the input quantum point contact (QPC) to the MZI. Moreover, at the same time a {\nu}_QPC =1/3 conductance plateau, carrying shot-noise, appeared in the transmission of the QPC - persisting until bulk filling {\nu}_B =1/2. We identified this conductance plateau to result from edge reconstruction, which leads to an upstream neutral mode. Here, we also show that even the particle-like quasiparticles are accompanied by upstream neutral modes, therefore suppressing interference in the FQHE regime., Comment: 16 pages, 13 figures

We report the synthesis of Mg0.5Zn0.5Fe2O4 (MZF) nanoparticles by gel combustion technique followed by fabrication of thin layer (~ 100 μm) of ferrite–polymer nanocomposite on aluminum substrate and its application on broadband absorption properties over the microwave frequency range of 4–15 GHz. The particle size of ferrite powder was controlled by changing citrate to nitrate molar ratios of precursors, which exhibit different adiabatic isotherms. XRD analysis showed that ferrite phase formation occurred for all systems and the system with lowest crystallite size (~ 30 nm) was obtained for the stoichiometric citrate to nitrate molar ratio. The nanocomposite coating showed excellent broadband absorption properties with absorptivity greater than 88%. This implied that the real and imaginary part of the surface impedance values of the nanocomposite coatings are close to 377 Ω and 0 Ω respectively, which is impedance of free space over the significant region of the frequency band of interest. The stoichiometric fuel based MZF of smallest average particle size showed best microwave absorption properties. The as-developed MZF nanocomposite coating showed minimum reflection from the coating over this frequency band, which can solve various electromagnetic interference issues, stealth technology, and the radiated EMI management in on board spacecraft and several others.

In recent interference experiments with an electronic Fabry-P\'erot interferometer (FPI), implemented in the integer quantum Hall effect regime, a flux periodicity of $h/2e$ was observed at bulk fillings ${\ensuremath{\nu}}_{B}g2.5$. The halved periodicity was accompanied by an interfering charge ${e}^{*}=2e$, determined by shot-noise measurements. Here, we present measurements demonstrating that, counterintuitively, the coherence and the interference periodicity of the interfering chiral edge channel are solely determined by the coherence and the enclosed flux of the adjacent edge channel. Our results elucidate the important role of the latter and suggest that a neutral chiral edge mode plays a crucial role in the pairing phenomenon. Our findings reveal that the observed pairing of electrons is not a curious isolated phenomenon, but one of many manifestations of unexpected edge physics in the quantum Hall effect regime.

In this paper, synthesis of Ni 0.5 Zn 0.5 Fe 2 O 4 nanoparticles via sol-gel process followed by fabrication of ultra-thin layer (90 μm) of ferrite-polymer nanocomposite on an aluminum (Al) substrate is carried out. The structural characterizations show that pure Ni-Zn ferrite phase formation occurred with average particles size of ∼ 19 nm. The nanocomposite coating shows excellent broadband absorption properties over the frequency range 4–15 GHz with absorptivity of greater than 85%. Simulations were performed for obtaining the optimum film-thickness of ferrite-nanocomposite and found that the return loss for varying thickness of ferrite layer was minimum for 5 μm thickness.

We consider the problem of streaming live content to a cluster of co-located wireless devices that have both an expensive unicast base-station-to-device (B2D) interface, as well as an inexpensive broadcast device-to-device (D2D) interface, which can be used simultaneously. Our setting is a streaming system that uses a block-by-block random linear coding approach to achieve a target percentage of on-time deliveries with minimal B2D usage. Our goal is to design an incentive framework that would promote such cooperation across devices, while ensuring good quality of service. Based on ideas drawn from truth-telling auctions, we design a mechanism that achieves this goal via appropriate transfers (monetary payments or rebates) in a setting with a large number of devices, and with peer arrivals and departures. Here, we show that a Mean Field Game can be used to accurately approximate our system. Furthermore, the complexity of calculating the best responses under this regime is low. We implement the proposed system on an Android testbed, and illustrate its efficient performance using real world experiments., To appear in IEEE/ACM Transactions on Networking. A preliminary version appeared in the proceedings of IEEE Infocom 2015

Landau damping, free from the influence of other forms of damping, has been experimentally detected in ion acoustic waves in traces of a dope plasma of a light inert gas, when it is introduced into partially ionized plasma of a heavy inert gas. A theory has been worked out of Landau damping for longitudinal waves in Vlasov plasma for study of this and other familiar Landau dampings.