Acoustically Induced Giant Synthetic Hall Voltages in Graphene.

Any departure from graphene's flatness leads to the emergence of artificial gauge fields that act on the motion of the Dirac fermions through an associated pseudomagnetic field. Here, we demonstrate the tunability of strong gauge fields in nonlocal experiments using a large planar graphene sheet that conforms to the deformation of a piezoelectric layer by a surface acoustic wave. The acoustic wave induces a longitudinal and a giant synthetic Hall voltage in the absence of external magnetic fields. The superposition of a synthetic Hall potential and a conventional Hall voltage can annihilate the sample's transverse potential at large external magnetic fields. Surface acoustic waves thus provide a promising and facile avenue for the exploitation of gauge fields in large planar graphene systems.

A single electron nanomechanical Y-switch.

We demonstrate current switching in the frequency domain using a nanomechanical shuttle with three terminals operating at room temperature. The shuttle consists of a metallic island on top of a Si nanopillar forming the Y-junction. A flexural mode of the nanopillar is excited by applying an external bias to one of the contacts, allowing electrons to be shuttled across the oscillating island.

Realizing broadbands of strong nonlinear coupling in nanoelectromechanical electron shuttles.

We demonstrate the transition of a coupled electron shuttle from a stable to a strongly nonlinear response at room temperature. Within this transition we observe the coupled shuttle's response to change from Coulomb controlled to conventional field emission. This parametric process is fully reversible and occurs within a broad frequency range. In combination, the large current and wide frequency band enable energy harvesting applications. The experimental data and the numerical calculations both indicate that the source of the nonlinearity is given by the electromechanical coupling of electron shuttling.

Coulomb blockade in a coupled nanomechanical electron shuttle.

We demonstrate single electron shuttling through two coupled nanomechanical pendula. The pendula are realized as nanopillars etched out of the semiconductor substrate. Coulomb blockade is found at room temperature, allowing metrological applications. By controlling the mechanical shuttling frequency we are able to validate the different regimes of electron shuttling.

[Interleukin-8 expression in lung tissue during ischemia-reperfusion]. / Estudio de la expresión de interleucina-8 en el tejido pulmonar durante la isquemia-reperfusión.

OBJECTIVE: Local cytokine production is a pathogenic factor in ischemia-reperfusion injury in early graft dysfunction. This study analyzed interleukin 8 (IL-8) messenger RNA (mRNA) expression in lung tissue and the association between IL-8 mRNA levels and interstitial lung changes in an experimental model of warm lung ischemia-reperfusion. MATERIAL AND METHODS: We studied 16 New Zealand rabbits divided into 3 groups: control, ischemia (tissue taken from right lower lobe after 1, 2, or 3 hours of ischemia), and reperfusion (tissue taken from right upper and middle lobes after 1 hour of ischemia and 1, 2, or 3 hours of reperfusion). Expression of IL-8 mRNA was determined by reverse transcription and polymerase chain reaction. Interstitial infiltration by polymorphonuclear neutrophils was determined. The Mann-Whitney U-test was used for statistical comparisons, with P< .05 considered to indicate a significant result. RESULTS: During ischemia, IL-8 mRNA levels were elevated at the end of hour 1 (P=.009) with respect to the control group, but not thereafter. Interstitial changes were minimal. IL-8 mRNA levels during reperfusion were similar to those observed during ischemia, with a slight increase at the end of hour 2. There were no significant differences between hours 1, 2, and 3. Polymorphonuclear neutrophil recruitment occurred at the beginning of reperfusion (P=.014), but no significant differences were observed at hours 2 or 3. Progressive thickening of alveolar septa and edema was documented. CONCLUSIONS: Changes in IL-8 mRNA expression during ischemia precede interstitial infiltration by polymorphonuclear neutrophils during reperfusion, suggesting that the 2 processes are related. Quantification of IL-8 mRNA expression could facilitate early diagnosis of graft dysfunction.

High precision quantum control of single donor spins in silicon.

The Stark shift of the hyperfine coupling constant is investigated for a P donor in Si far below the ionization regime in the presence of interfaces using tight-binding and band minima basis approaches and compared to the recent precision measurements. In contrast with previous effective mass-based results, the quadratic Stark coefficient obtained from both theories agrees closely with the experiments. It is also shown that there is a significant linear Stark effect for an impurity near the interface, whereas, far from the interface, the quadratic Stark effect dominates. This work represents the most sensitive and precise comparison between theory and experiment for single donor spin control. Such precise control of single donor spin states is required particularly in quantum computing applications of single donor electronics, which forms the driving motivation of this work.