CPAP Hardware/Simulation and Control Design for Respiratory Disorders: A Review

Continuous Positive Airway Pressure (CPAP) ventilation remains a mainstay treatment for different respiratory disorders. Good pressure stability and pressure reduction during exhalation are of major importance condition to ensure the clinical efficacy and comfort of CPAP therapy. Obstructive Sleep Apnea (OSA) and today coronavirus (COVID-19) are the main two diseases mitigated by the CPAP. This paper introduced a systematic review of the CPAP design in terms of the hardware design, Simulation-based CPAP system, control algorithm, and the measured performance. The accuracy is used as measurement of performance and calculated from the pressure value. The accuracy was compared to the predefined U.S. Food and Drug Administration (FDA)-based threshold value in which it considers this value as a reference. The results related to the modern CPAP devices introduced in this study to explain the accuracy of experimental CPAP. These were compared with a commercial CPAP devices. Also, it was revealed how the results coincide with the error ratio defined by the FDA as an evaluation measurement. The FDA error ratio determines the performance of the optimized CPAP device. This work is the first review that presented the knowledge about engineering design of the CPAP system, so it will be the first in the literature.

Unconventional Stoichiometries of Na–O Compounds at High Pressures

It has been realized that the stoichiometries of compounds may change under high pressure, which is crucial in the discovery of novel materials. This work uses systematic structure exploration and first-principles calculations to consider the stability of different stoichiometries of Na–O compounds with respect to pressure and, thus, construct a high-pressure stability field and convex hull diagram. Four previously unknown stoichiometries (NaO5, NaO4, Na4O, and Na3O) are predicted to be thermodynamically stable. Four new phases (P2/m and Cmc21 NaO2 and Immm and C2/m NaO3) of known stoichiometries are also found. The O-rich stoichiometries show the remarkable features of all the O atoms existing as quasimolecular O2 units and being metallic. Calculations of the O–O bond lengths and Bader charges are used to explore the electronic properties and chemical bonding of the O-rich compounds. The Na-rich compounds stabilized at extreme pressures (P > 200 GPa) are electrides with strong interstitial electron localization. The C2/c phase of Na3O is found to be a zero-dimensional electride with an insulating character. The Cmca phase of Na4O is a one-dimensional metallic electride. These findings of new compounds with unusual chemistry might stimulate future experimental and theoretical investigations.

Statistical quality control to emission uniformity in micro sprinkler with autonomous photovoltaic pumping

This work aimed to evaluate a microsprinkler irrigation system using photovoltaic energy without energy storage. The influence of photovoltaic pumping on irrigation was evaluated from the Emission Uniformity, Shewhart control charts and Process Capacity. The experiment consisted of two amorphous photovoltaic panels connected in parallel, directly connected to a water pump, where the flow of the pumping system was carried out through a ½” tube (main line), to the irrigation system composed of four microsprinklers. The voltage and current parameters were collected, and the power of the photovoltaic system was calculated, while for the irrigation system the pressures of the four microsprinklers were measured to later calculate the flow rate of the irrigation system. The experiment was conducted at the State University of Western Paraná, UNIOESTE, where 25 days of collection were carried out, in the open, at four different times, from 10:00 am to 11:00 am, from 11:05 am to 12:05 pm, from 2:00 pm to 3:00 pm and from 3:05 pm to 4:05 pm . Power generation presented a low coefficient of variation throughout the day, which resulted in flow and pressure stability, culminating in an Emission Uniformity (UE) value qualified as excellent (93.66%) according to the ASAE. The values of energy generation, flow, pressure, and emission uniformity presented a Process Capacity (CP) value above 1.33, defining the process as capable and adequate throughout the analyzed period.

High-pressure behavior of disodered kesterite-type Cu2ZnSnS4

We have investigated the high-pressure structural and vibrational behavior of the disordered kesterite-type Cu2ZnSnS4 compound at ambient temperature. Our experimental and theoretical investigations have revealed a clear structural transition to a GeSb-type phase close to 15 GPa, a tetragonally distorted variant of the NaCl-type phase. The latter transformation is accompanied by a cationic coordination increase from fourfold to sixfold with respect to the sulfur anions. In addition, a change in the compressibility rate was detected at about 8 GPa within the pressure stability range of the disordered kesterite-type phase. Upon decompression, a disordered zinc blende/sphalerite structure is recovered. We discuss our findings in close conjunction with our recent high-pressure work on the ordered Cu2ZnSnS4 modification.

Abstract P637: Blood Pressure Stability Has a Closer Relationship With Atherosclerosis Burden of Carotid Sinuses Than Atherosclerosis Burden of Aortic Arch

Background: Instable blood pressure (BP) increased vascular risk independently of high BP level, which might be partially attributed to impaired arterial baroreflex. The receptors of baroreflex mainly distributed at carotid sinuses and aortic arch, where atherosclerosis (AS) is common in patients with ischemic stroke (IS) and potentially blunts the baroreflex. We aimed to test whether AS conditions of carotid sinuses and aortic arch would equally indicate BP instability in IS patients. Methods: The daytime and nighttime standard derivations (SDs) of systolic BP (SBP) and diastolic BP (DBP) were recorded by ambulatory BP monitoring on the sixth day after IS to measure BP stability (higher SD indicates less stability). Using computed tomography angiography, AS conditions of carotid sinuses (6 segments) and aortic arch (4 segments) were scored based on AS percentage of each segment circumference (0, none; 1, <25%; 2, 25%~49%; 3, 50%~74%; 4, ≥75%) and summed into “carotid sinuses AS burden (CSAB)” and “aortic arch AS burden (AAAB)”. AS conditions of cervicocephalic arteries were also scored. Results: Of the 245 patients with IS, 65.7% had carotid sinuses AS and 69.4% had aortic arch AS. Daytime SBP SD was positively correlated with CSAB ( r =0.230; P <0.001) rather than AAAB ( P =0.103). Patients with CSAB above the median had significantly higher daytime SBP SD than those with less CSAB (median 14 mmHg vs. 12 mmHg, P =0.001). CSAB remained related to ln- transformed daytime SBP SD after adjusting for age, sex, vascular risk factors, weighted 24-hour means of SBP and DBP, and cervicocephalic AS score (adjusted B =0.012; 95% CI, 0.004-0.020). In contrast, DBP SD and nighttime SBP SD had no statistically significant association with both CSAB and AAAB. Conclusions: Higher CSAB was independently associated with SBP instability during the daytime, while AAAB was less relevant to BP stability. Compared with AAAB, evaluating CSAB might be more important in the prediction of BP instability.