Development of a Novel Anesthesia Airway Management Robot

Non-invasive positive pressure ventilation has attracted increasing attention for air management in general anesthesia. This work proposes a novel robot equipped with two snake arms and a mask-fastening mechanism to facilitate trachea airway management for anesthesia as well as deep sedation and to improve surgical outcomes. The two snake arms with supporting terminals have been designed to lift a patient’s jaw with design optimization, and the mask-fastening mechanism has been utilized to fasten the mask onto a patient’s face. The control unit has been developed to implement lifting and fastening force control with safety and robustness. Loading experiments on the snake arm and tension experiments on the mask-fastening mechanism have been performed to investigate and validate the performances of the proposed anesthesia airway management robot. Experiments on a mock person have also been employed to further verify the effectiveness and reliability of the developed robot system. As an early study of an anesthesia airway management robot, it was verified as a valid attempt to perform mask non-invasive positive pressure ventilation technology by taking advantage of a robotic system.

Hyperlipidemia impairs uterine β-adrenergic signaling by reducing cAMP in late pregnant rats

The aim of the present study was to reveal the effect of hyperlipidemia on β2- and β3-adrenergic signaling in late pregnant rat uterus. Hyperlipidemia was induced in female Wistar rats by feeding a high-fat high-cholesterol diet for 8 weeks before and after mating upto the 21st day of gestation. The effect of hyperlipidemia on β-adrenergic signaling was studied with the help of tension experiments, real-time PCR and cAMP ELISA in 21-day pregnant rat uterus. In tension experiments, hyperlipidemia neither altered the spontaneous contractility nor the oxytocin-induced contractions. However, it decreased the −logEC50 values of β2-adrenoceptor agonist, salbutamol and β3-adrenoceptor agonist, BRL37344. It also decreased the efficacy of adenylyl cyclase activator, forskolin. Further, there was a significant decrease in salbutamol and BRL37344-stimulated cAMP content in uterine tissues. However, there was no alteration in mRNA expressions of β2-adrenoceptor (Adrb2), β3-adrenoceptor (Adrb3) and Gs protein (Gnas) though there was a significant increase in the mRNA expression of Gi protein (Gnai). In conclusion, reduced cAMP content after beta-adrenergic receptor stimulation, which correlates with an increase in Gnai mRNA, may explain the mechanism of the impairment of uterine β-adrenergic signaling in hyperlipidemic pregnant rats. The clinical implication of the present study may relate to reduced myometrial relaxant response to β-adrenergic agonists in high fat-induced uterine dysfunction.

P5373Mechanical heterogeneity across the left ventricular wall - a study using intact multicellular preparations

Introduction The importance of transmural heterogeneity for left ventricular (LV) function is well recognised. Mid-wall systolic shortening is a better predictor of cardiovascular morbidity than ejection fraction. While variation in electrical properties is well-documented, transmural mechanical differences remain poorly characterised. Most studies are based on isolated cells or permeabilised preparations, with limited data acquired in living multicellular myocardial preparations. Purpose Here, we test the hypothesis that heterogeneity in intrinsic mechanical properties exists across the LV wall. We use a novel intact organotypic preparation, myocardial slices, from different layers of the ventricular wall. Methods 300μm-thick living tangential myocardial slices with preserved structure and function were sequentially obtained from LVs of adult male Sprague-Dawley rats using a high precision vibrating microtome. Each slice corresponded to a different layer of the LV wall. Slices from endo-, mid- and epicardium were used (Fig 1C). To rule out transmural differences in Ca2+ -response, force-Ca2+ experiments were first performed on slices at 2.1μm sarcomere length (SL) with a half-log [Ca2+] (10–3.5 to 10–2.0 M) in the supernatant. SL-tension experiments were then conducted by measuring steady state force of isometrically twitching slices at 2.00-, 2.10-, 2.20-, 2.25-, 2.35-, & 2.40μm SL in Tyrode solution containing the EC50 [Ca2+], determined from the force-Ca2+ experiments. Analysis of co-variance and two-way ANOVA with Turkey post-hoc were used for statistical comparisons. Results Force-Ca2+ data were fit with a variable hill-slope. As no differences in the EC50 of endo-, mid-, and epi- slices (n=6, 5, 4) were found, length-tension experiments were performed at a common EC50 [Ca2+] (10–2.54 M). Increasing SL increased developed tension in all slices. However, mid- generated significantly greater tension than endo- at 2.25-, 2.35-, & 2.40μm SL but not epi- slices (p=0.006, 0.045, 0.048 respectively) (Fig 1A). A linear regression was fit to the SL-active tension data of the different layers. Epi- had significantly steeper slope than endo- (p=0.0137) suggesting greater ability to respond to stretch (n=6, 5, 6) (Fig 1B). Increasing SL increased passive tension in all slices. Epi- was significantly stiffer than endo- at 2.35- & 2.40μm SL (p=0.023, 0.0002 respectively). Mid- was also significantly stiffer than endo- at 2.40μm SL (p=0.0007) (n=6, 5, 6) (Fig 1A). Figure 1. A: SL-Tension; B: Slopes; C: Schematic Conclusions Here, we demonstrate for the first time the use of myocardial slices for investigation of transmural mechanics in intact adult cardiac tissue. We show that both active and passive mechanical properties differ across the LV wall. Coupled with transmural electrical differences, mechanical heterogeneity may act to orchestrate the normal operation of the whole heart. In disease, loss of heterogeneity may contribute to impaired LV function and accelerate clinical deterioration. Acknowledgement/Funding British Heart Foundation (MBBS PhD Studentship FS/18/37/33642)

Numerical analysis of the influence of the damping rings' thickness on interrupted dynamic tension results using SiC-reinforced ZC71 magnesium alloy specimens

This article discusses the influence of the thickness of the damping rings used for interrupting a dynamic tension experiments on the results of a modified split Hopkinson tension bar (SHTB). In this paper a device enclosed in an external fixture used for interrupting a dynamic tension experiment in a SHTB is studied. The novelty of this manuscript with respect to previous studies lies in the fact that the dynamic tension experiment in a SHTB is interrupted in order to study the mechanical behavior of the material at high strain rates. The role played by such device is to interrupt the experiment at different levels of plastic deformation, particularly when the specimen is about to reach its failure strength. Finite-element (FE) simulations of high-strain-rate tension experiments are accomplished on a particle-reinforced metal matrix composite specimen (namely SiC-reinforced ZC71 magnesium alloy) when varying the thickness of the damping rings. Interrupting the test before the specimen breaks offers the possibility of being able to study in a more detailed way the deformation process of such material at high strain rates. Therefore, this work focuses on the study of the behaviour of materials undergoing high strain rates, developing a tool which allows materials to withstand different levels of strain rates in a controlled manner and providing guidance for future studies. In view of this research, it can be concluded that the thickness of the damping rings is a factor that can resolutely influence the interrupted dynamic tension experiment results avoiding the specimen's failure by optimally buffering the experiment using 0.8 mm thick lead damping rings.

Исследование влияния размеров образцов на скорость деформации при определении прочностных динамических характеристик материала

Test results are presented for an additive material prepared of acrylonitrile-butadiene-styrene on a 3D printer. Dynamic tension experiments have been carried out using a tower-type drop hammer with an accelerator. Data obtained from different specimens demonstrate that high-strain-rate tensile experiments are feasible if the working part of the specimen is decreased. A theoretical analysis of test data using the incubation time criterion has been performed, and it has been found that analytical results are in good agreement with experimental data.

Mechanical Fatigue Resistance of Piezoelectric PVDF Polymers

The fatigue resistance of piezoelectric PVDF has been under question in recent years. While some report that a significant degradation occurs after 106 cycles of repeated voltage input, others report that the reported degradation originates from the degraded metal electrodes instead of the piezoelectric PVDF itself. Here, we report the piezoelectric response and remnant polarization of PVDF during 107 cycles of repeated compression and tension, with silver paste-based electrodes to eliminate any electrode effect. After applying repeated tension and compression of 1.8% for 107 times, we do not observe any notable decrease in the output voltage generated by PVDF layers. The results from tension experiments show stable remnant polarization of 5.5 μC/cm2, however, the remnant polarization measured after repeated compression exhibits a 7% decrease as opposed to the tensed PVDF. These results suggest a possible anisotropic response to stress direction. The phase analyses by Raman spectroscopy reveals no significant change in the phase content, demonstrating the fatigue resistance of PVDF.