Performance of emergency mechanical ventilators in response to the covid-19 pandemic: an intercomparison study.

Emergency mechanical ventilators developed during the pandemic were used to meet the high demand in intensive care units to care for COVID-19 patients. An example of such ventilators is Masi, developed in Peru and installed in more than 15 hospitals around the country. This study aimed to compare Masi's performance with other emergency mechanical ventilators manufactured during the covid-19 pandemic such as Neyün, Spiro Wave and a prototype developed by the Faculty of Engineering of the National University of Asuncion (FIUNA). Three configurations of a test lung were used, combining different values of resistance and compliance (C1, C2 and C3). Ventilators were set to volume-controlled ventilation with tidal volume = 400 mL, respiratory rate = 12 breaths/minute, and positive end-expiratory pressure (PEEP) = 8 cm H2O. These parameters were measured in a series of ten two-minute tests which then were evaluated through a two-way analysis of variance, considering the type of ventilator and test lung configuration as the two independent variables. For target values, MASI delivered VT that ranged from 319 to 432 ml (-20 to +8%), respiratory rate of 12 bpm, and PEEP from 8.4 to 9.5 cm H2O (+5 to +20%). In contrast, for instance, Neyün delivered VT that ranged from 199 to 543 ml (-50 to +35%) and PEEP from 7.05 to 9.21 cm H2O (--11 to +15%), with p<0.05. The analysis of variance showed that he differences between preset and delivered parameters were influenced by the type of ventilator and, significantly, by the test lung configuration.Clinical Relevance- This establishes the most advantageous conditions in which three emergency mechanical ventilators work and a quantitative perspective in this topic.

Manifestation of Kinetic Inductance in Terahertz Plasmon Resonances in Thin-Film Cd3As2.

Three-dimensional (3D) semimetals have been predicted and demonstrated to have a wide variety of interesting properties associated with their linear energy dispersion. In analogy to two-dimensional (2D) Dirac semimetals, such as graphene, Cd3As2 has shown ultrahigh mobility and large Fermi velocity and has been hypothesized to support plasmons at terahertz frequencies. In this work, we experimentally demonstrate synthesis of high-quality large-area Cd3As2 thin films through thermal evaporation as well as the experimental realization of plasmonic structures consisting of periodic arrays of Cd3As2 stripes. These arrays exhibit sharp resonances at terahertz frequencies with associated quality factors ( Q) as high as ∼3.7 (at 0.82 THz). Such spectrally narrow resonances can be understood on the basis of a long momentum scattering time, which in our films can approach ∼1 ps at room temperature. Moreover, we demonstrate an ultrafast tunable response through excitation of photoinduced carriers in optical pump/terahertz probe experiments. Our results evidence that the intrinsic 3D nature of Cd3As2 might provide for a very robust platform for terahertz plasmonic applications. Moreover, the long momentum scattering time as well as large kinetic inductance in Cd3As2 also holds enormous potential for the redesign of passive elements such as inductors and hence can have a profound impact in the field of RF integrated circuits.