improving the performance of wind turbines in urban environment by integrating the action of a diffuser with the aerodynamics of the rooftops

Abstract We investigated the effectiveness of combining the concentration effects generated by a dual-pitched roof and a diffuser-shaped wall mounted over a Darrieus turbine, which is rooftop mounted with horizontal shaft running close to the roof ridge. A2D CFD study was carried out in three steps: (1) we predicted the turbine basic performance with and without a convergent-divergent diffuser in a infinite and undisturbed domain; (2) the behavior of the concentration system on the rooftop were simulated in a simplified urban contest; (3) we improved both the operating conditions and the domain geometry to make them more similar to realistic urban environments. The simulations are performed by means a fully URANS since both the turbine aerodynamic forces and the urban wind field are simulated. Results show that by integrating the actions of rooftop and diffuser a significant power increasing is obtained in skewed winds. Moreover, the diffuser allows a drastic abatement of torque fluctuations

WITHDRAWN: A subacute case of traumatic avulsion of the flexor digitorum pofundus tendon due to recurrent enchondroma of the distal phalanx

Abstract Avulsion of the flexor digitorum profundus (FDP) tendon associated to an enchondroma fracture in the distal phalanx is very rare. We report a subacute case of a type II FDP tendon avulsion of the small finger at its insertion, in combination with a fracture of the distal phalanx due to enchondroma. The bone lesion was curated and grafted using autogenous bone harvested from the ipsilateral radius. The FDP tendon was reattached to the distal phalanx using the pullout transosseous technique. Delayed protected active mobilization was used to treat the repaired tendon. According to the adjusted Strickland score, a good result was obtained and grip strength was similar between hands and PRWHE score was very low at 5 months from surgery. Early diagnosis leads to a fast surgery with good functional mobility and pain outcomes. If closely monitored by an experienced medical team, as this case demonstrates, an attempt to treat the benign tumor with a curettage, bone filling and reattachment of the tendon through the pullout technique in young motivated patients can be an alternative

Impact of DC Transient Disturbances on Harmonic Performance of Voltage Transformers for AC Railway Applications

This paper analyzes the impact of typical DC transient events occurring in railway grids on the frequency performance of instrument transformers (ITs) installed onboard trains and in AC substations for power quality (PQ) applications. PQ monitoring in railway systems is an issue of great interest because it plays a key role in the improvement of energy efficiency. The measurement chain for the PQ measurements, at 15 kV at 16.7 Hz and 25 kV at 50/60 Hz, commonly includes ITs to scale the voltage to levels fitting the input of the measurement units. Nevertheless, the behavior of ITs in the presence of PQ phenomena represents an open issue from a normative point of view, even for those installed in conventional AC power supply systems. In this context, the paper presents a possible definition of DC transient disturbances test waveforms, a measurement procedure, and a setup to assess the impact of these disturbances on the harmonic performances of ITs for railway systems. Preliminary experimental tests carried out on two commercial ITs under wide ranges of variation for the amplitude and the time duration of DC disturbances show that, in some cases, the error introduced in harmonic measurements can exceed 100%

N-acetylcysteine serves as substrate of 3-mercaptopyruvate sulfurtransferase and stimulates sulfide metabolism in colon cancer cells

Hydrogen sulfide (H2S) is an endogenously produced signaling molecule. The enzymes 3-mercaptopyruvate sulfurtransferase (MST), partly localized in mitochondria, and the inner mitochondrial membrane-associated sulfide:quinone oxidoreductase (SQR), besides being respectively involved in the synthesis and catabolism of H2S, generate sulfane sulfur species such as persulfides and polysulfides, currently recognized as mediating some of the H2S biological effects. Reprogramming of H2S metabolism was reported to support cellular proliferation and energy metabolism in cancer cells. As oxidative stress is a cancer hallmark and N-acetylcysteine (NAC) was recently suggested to act as an antioxidant by increasing intracellular levels of sulfane sulfur species, here we evaluated the effect of prolonged exposure to NAC on the H2S metabolism of SW480 colon cancer cells. Cells exposed to NAC for 24 h displayed increased expression and activity of MST and SQR. Furthermore, NAC was shown to: (i) persist at detectable levels inside the cells exposed to the drug for up to 24 h and (ii) sustain H2S synthesis by human MST more effectively than cysteine, as shown working on the isolated recombinant enzyme. We conclude that prolonged exposure of colon cancer cells to NAC stimulates H2S metabolism and that NAC can serve as a substrate for human MST

Towards a comprehensive understanding of brain machinery by correlative microscopy.

Unraveling the complexity of brain structure and function is the biggest challenge of contemporary science. Due to their flexibility, optical techniques are the key to exploring this intricate network. However, a single imaging technique can reveal only a small part of this machinery due to its inherent multilevel organization. To obtain a more comprehensive view of brain functionality, complementary approaches have been combined. For instance, brain activity was monitored simultaneously on different spatiotemporal scales with functional magnetic resonance imaging and calcium imaging. On the other hand, dynamic information on the structural plasticity of neuronal networks has been contextualized in a wider framework combining two-photon and light-sheet microscopy. Finally, synaptic features have been revealed on previously in vivo imaged samples by correlative light-electron microscopy. Although these approaches have revealed important features of brain machinery, they provided small bridges between specific spatiotemporal scales, lacking an omni-comprehensive view. In this perspective, we briefly review the state of the art of correlative techniques and propose a wider methodological framework fusing multiple levels of brain investigation

Multi-Photon Nanosurgery in Live Brain

In the last few years two-photon microscopy has been used to perform in vivo high spatial resolution imaging of neurons, glial cells and vascular structures in the intact neocortex. Recently, in parallel to its applications in imaging, multi-photon absorption has been used as a tool for the selective disruption of neural processes and blood vessels in living animals. In this review we present some basic features of multi-photon nanosurgery and we illustrate the advantages offered by this novel methodology in neuroscience research. We show how the spatial localization of multi-photon excitation can be exploited to perform selective lesions on cortical neurons in living mice expressing fluorescent proteins. This methodology is applied to disrupt a single neuron without causing any visible collateral damage to the surrounding structures. The spatial precision of this method allows to dissect single processes as well as individual dendritic spines, preserving the structural integrity of the main neuronal arbor. The same approach can be used to breach the blood-brain barrier through a targeted photo-disruption of blood vessels walls. We show how the vascular system can be perturbed through laser ablation leading toward two different models of stroke: intravascular clot and extravasation. Following the temporal evolution of the injured system (either a neuron or a blood vessel) through time lapse in vivo imaging, the physiological response of the target structure and the rearrangement of the surrounding area can be characterized. Multi-photon nanosurgery in live brain represents a useful tool to produce different models of neurodegenerative disease