We report on the superior electrochemical properties, in-vivo performance and long term stability under electrical stimulation of a new electrode material fabricated from lithographically patterned ...glassy carbon. For a direct comparison with conventional metal electrodes, similar ultra-flexible, micro-electrocorticography (μ-ECoG) arrays with platinum (Pt) or glassy carbon (GC) electrodes were manufactured. The GC microelectrodes have more than 70% wider electrochemical window and 70% higher CTC (charge transfer capacity) than Pt microelectrodes of similar geometry. Moreover, we demonstrate that the GC microelectrodes can withstand at least 5 million pulses at 0.45 mC/cm
charge density with less than 7.5% impedance change, while the Pt microelectrodes delaminated after 1 million pulses. Additionally, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) was selectively electrodeposited on both sets of devices to specifically reduce their impedances for smaller diameters (<60 μm). We observed that PEDOT-PSS adhered significantly better to GC than Pt, and allowed drastic reduction of electrode size while maintaining same amount of delivered current. The electrode arrays biocompatibility was demonstrated through in-vitro cell viability experiments, while acute in vivo characterization was performed in rats and showed that GC microelectrode arrays recorded somatosensory evoked potentials (SEP) with an almost twice SNR (signal-to-noise ratio) when compared to the Pt ones.
Structural biocompatibility is a fundamental requirement for chronically stable bioelectronic devices. Newest neurotechnologies are increasingly focused on minimizing the foreign body response ...through the development of devices that match the mechanical properties of the implanted tissue and mimic its surface composition, often compromising on their robustness. In this study, an analytical approach is proposed to determine the threshold of conformability for polyimide-based electrocorticography devices. A finite element model was used to quantify the depression of the cortex following the application of devices mechanically above or below conformability threshold. Findings were validated in vivo on rat animal models. Impedance measurements were performed for 40 days after implantation to monitor the status of the biotic/abiotic interface with both conformable and non-conformable implants. Multi-unit activity was then recorded for 12 weeks after implantation using the most compliant device type. It can therefore be concluded that conformability is an essential prerequisite for steady and reliable implants which does not only depend on the Young's modulus of the device material: it strongly relies on the relation between tissue curvature at the implantation site and corresponding device's thickness and geometry, which eventually define the moment of inertia and the interactions at the material-tissue interface.
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•We have identified key factors for increasing the conformability of PI-based implants and their bio-stability over time.•The device thickness should be tailored to the target anatomical area.•An open architecture footprint (sieve-like) should be preferred to a solid one.•IrOx and PEDOT/PSS are reliable materials for chronic multi-spike recordings.•Electrodes with diameter ≤ 100 μm are expected to work similarly in chronic implants.
•Medium voltage underground cables and joints failures.•Electrical resilience of MV distribution network.•Laboratory tests on MV cables and accessories.
MV underground cable systems are one of the ...main assets in electrical distribution infrastructures in densely populated urban areas. Experience of several distribution operators (DSOs) has shown an increasing number of failures of MV underground cable joints in the summer period. e-distribuzione, the main Italian DSO, and the University of Roma “La Sapienza” have investigated the causes of these joints failures, ran a temperature measurement campaign on cable joints and performed experimental inspections on both failed and not-failed cable joints. Field observations have been compared with the failure statistics of pre-qualification, type testing and testing after installation of power cables and accessories at KEMA Labs. The relatively high number of failures in testing proves the importance of these tests and awards an insight into failure mode. In this paper are reported the main results of a temperature measurement campaign on such MV underground cable joints and an experimental inspection on both failed and not failed cable joints. In this contribution, a discharge mechanism and the ongoing adopted mitigation actions are also presented. The gained information will be useful in re-designing innovative MV underground cable joints for a more resilient distribution system.
Abstract
Background and Aims
Low-weight extracorporeal pediatric dialysis treatments remain a challenge due to their clinical and technical complexity.
Apart from some metabolic congenital disorders, ...the usual indications for CRRT in early pediatric patients and newborns are the same as for adults with acute kidney injury (AKI). But the implementation of TPE is still in the anecdotal stage.
Method
Clinical case: a 7-month female infant, weighing 5.7kg, in the neonatal intensive care unit with fever, lymphadenopathy, hepatosplenomegaly, pancytopenia, hyperferritinemia, hypertriglyceridemia, was diagnosed as having macrophage activation syndrome (MAS). She developed AKI and acute respiratory distress syndrome (ARDS), due to sepsis. Because of oliguria, ruling out administration of drugs and parental nutrition, and fluid overload (more than 20% of her body-weight), CRRT was started.
Results
CRRT lasted 22 days in continuous venovenous hemodiafiltration (CVVHDF), with regional citrate anticoagulation (Table 1). Mean filter patency: 26±17h. 43% of treatments were interrupted after CVC failure, 21% after clinical procedures, 7% after filter coagulation. There was in this case no citrate accumulation and satisfactory metabolic and electrolyte control were obtained (Figure 1).
After treatment of MAS failed with both i.v. immunoglobulins and corticosteroids, we considered TPE as a rescue therapy for the disease, even though we could not find a similar experience reported in the literature in such a small infant. We performed 3 TPE sessions, with heparin anticoagulation (Table 1), non-consecutively, with CRRT in between.
Conclusion
The treatments were well tolerated, resulting in a large decrease in triglycerides and ferritin (MAS index, Figure 2).
Despite the death of the patient after ARDS worsened, we showed that even in a small critically ill infant, complex depurative treatments such as total plasma exchange are feasible. Highly skilled nephrologists and dialysis nurses are mandatory for treatment management.
Abstract
Background and Aims
Prolonged mechanical ventilation is associated with the risk of difficult weaning due to the onset of muscle weakness. A disproportion occurs between the respiratory ...workload and the muscular force, which leads to failure of the ventilatory pump and hypercapnia. Some early experiences suggest that ECCO2R facilitates weaning from the ventilator in patients with a high risk of failure.
Method
Clinical case: a 49 year-old man with a) recent orthotopic liver transplantation (cryptogenic cirrhosis), b) acute renal injury (AKI) on continuous veno-venous hemofiltration (CVVH) and c) acute respiratory distress syndrome (ARDS) requiring prolonged mechanical ventilation. After unsuccessful attempts at weaning from the ventilator, a lung membrane was inserted in series, before the hemofilter, on the CRRT circuit in order to remove CO2 and so reduce the workload of the respiratory muscles (Fig. 1). The patient was then extubated. We used citrate anticoagulation due to the presence of contraindications to systemic heparin (high bleeding risk, thrombocytopenia).
Results
ECCO2R + CRRT treatment requires a relatively high blood flow (300-350 ml / min) in order to extract a significant amount of CO2, but, the more the blood flow increases, the more citrate must be infused, and the more the metabolic load increases. The patient developed mild alkalosis as an initial sign of citrate accumulation (Table 1), but it was self-limiting. During ECCO2R we actually obtained the desired decrease in respiratory muscle effort (decrease in respiratory rate from 24 to 18 per minute and a maximum negative value of esophageal pressure from -8 to -4 cmH2O) and the treatment was interrupted after 36 hours. Mechanical ventilation was restored due to a complication independent of ECCO2R (massive pneumothorax). The patient tolerated the treatment for 36 hours.
Conclusion
ECCO2R proved an efficient and relatively simple technology helping respiratory function recovery. Due to the very frequent association of AKI and ARDS, leading to a high mortality rate, nephrological care in intensive care units should include this new treatment. Moreover, reduction of the inflammatory pathway secondary to mechanical ventilation could also benefit the evolution of AKI.
Figure:
Abstract
We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). We used the Hubble Space Telescope (HST) to carry out precise astrometry of the ...source star of the long-duration (
t
E
≃ 270 days), high-magnification microlensing event MOA-2011-BLG-191/OGLE-2011-BLG-0462 (hereafter designated as MOA-11-191/OGLE-11-462), in the direction of the Galactic bulge. HST imaging, conducted at eight epochs over an interval of 6 yr, reveals a clear relativistic astrometric deflection of the background star’s apparent position. Ground-based photometry of MOA-11-191/OGLE-11-462 shows a parallactic signature of the effect of Earth’s motion on the microlensing light curve. Combining the HST astrometry with the ground-based light curve and the derived parallax, we obtain a lens mass of 7.1 ± 1.3
M
⊙
and a distance of 1.58 ± 0.18 kpc. We show that the lens emits no detectable light, which, along with having a mass higher than is possible for a white dwarf or neutron star, confirms its BH nature. Our analysis also provides an absolute proper motion for the BH. The proper motion is offset from the mean motion of Galactic disk stars at similar distances by an amount corresponding to a transverse space velocity of ∼45 km s
−1
, suggesting that the BH received a “natal kick” from its supernova explosion. Previous mass determinations for stellar-mass BHs have come from radial velocity measurements of Galactic X-ray binaries and from gravitational radiation emitted by merging BHs in binary systems in external galaxies. Our mass measurement is the first for an isolated stellar-mass BH using any technique.
Hybrid Organic‐Inorganic Halide Perovskites (HOIHPs) represent an emerging class of semiconducting materials, widely employed in a variety of optoelectronic applications. Despite their skyrocket ...growth in the last decade, a detailed understanding on their structure‐property relationships is still missing. In this communication, we report two unprecedented perovskite‐like materials based on polyfluorinated imidazolium cations. The two materials show thermotropic liquid crystalline behavior resulting in the emergence of stable mesophases. The manifold intermolecular F⋅⋅⋅F interactions are shown to be meaningful for the stabilization of both the solid‐ and liquid‐crystalline orders of these perovskite‐like materials. Moreover, the structure of the incorporated imidazolium cation was found to tune the properties of the liquid crystalline phase. Collectively, these results may pave the way for the design of a new class of halide perovskite‐based soft materials.
•Oxidized Single Walled Carbon Nanohorns-PEDOT/PSS (NHs) composite was electrodeposited onto neural microelectrodes.•A comparison with Oxidized Multi Walled Carbon Nanotubes-PEDOT/PSS (NTs) ...composites was furnished.•Higher Charge Injection limit was observed for NHs.•Similar neural sensing capability and cell viability were obtained for both NHs and NTs.
Oxidized single walled carbon nanohorns (ox-SWCNH) were electrodeposited onto gold microelectrode arrays in conjunction with poly(3,4-ethylenedioxythiophene) (PEDOT) and polystirenesulfonate (PSS), and the properties of the new composite material for neural recording and stimulation were assessed. PEDOT/ox-SWCNH composites were compared with films prepared with one of the most notorious carbonaceous material in this field, the oxidized multi-walled Carbon Nanotubes (ox-MWCNT). The PEDOT/ox-SWCNH exhibited superior charge transfer capability, reflecting greater electroactive surface, as confirmed by SEM and EIS characterizations. As a consequence, a charge injection limit of 11.6 mC/cm2 was observed for the new composite, which is higher than the one of PEDOT/ox-MWCNT (8.7 mC/cm2). Having confirmed comparable neural recording performance, the PEDOT/ox-SWCNH composite results very promising for improving therapeutic electrical stimulation in the central and peripheral nervous systems.
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