Decreasing Oxygen Pressure Research Articles

FLIGHT HOURS AND BMI AGAINST TUC IN HYPOBARIC CHAMBER ALTITUDE 25.000 FEET

Background: Time of Useful Consciousness (TUC) is the time interval a person can survive carrying out flight duties due to a decrease in oxygen pressure and the point at which there is a decrease in the level of consciousness. The TUC time interval is influenced by various factors including Body Mass Index (BMI) and flying hours which affect the increase in the duration of the body's exposure to hypoxic conditions in pilots. Purpose: This research was conducted to determine the relationship between total flight hours and BMI on TUC. Method: This research employed observational analytic research with a cross-sectional method. Sampling was taken by simple random sampling technique. The sample for this research included active flight crew members from Lakespra dr. Saryanto 202 who met the inclusion criteria. Result: There were 53 research subjects, with the results showing that 48 subjects (90.6%) had a TUC <4 minutes, and 5 subjects had a TUC >4 minutes. There were 47 subjects (88.7%) with total flight hours >1000 hours and 6 subjects (11.3%) with total flight hours <1000 hours. In BMI, 37 subjects (69.8%) had an overweight BMI, and 16 subjects (30.2%) had a normal BMI. Conclusion: After examining 53 subjects, it was found that there was no relationship between total flight hours and TUC (p-value = 1.000) or BMI and TUC( p-value = 0.307) in the hypobaric chamber at an altitude of 25.000 feet.

Differences in Exercise Capacity, Ventilatory Efficiency, and Gas Exchange between Patients with Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension Residing at High Altitude.

Cardiopulmonary exercise testing (CPET) assesses exercise capacity and causes of exercise limitation in patients with pulmonary hypertension (PH). At altitude, changes occur in the ventilatory pattern and a decrease in arterial oxygen pressure in healthy; these changes are increased in patients with cardiopulmonary disease. Our objective was to compare the response to exercise and gas exchange between patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) residing at the altitude of Bogotá (2640 m). All patients performed an incremental CPET with measurement of oxygen consumption ( ), dead space (VD/VT), ventilatory equivalents (VE/ ), and alveolar-arterial oxygen gradient ( ). test and one-way analysis of variance were used for comparisons between PAH and CTEPH. We included 53 patients, 29 with PAH, 24 with CTEPH, and 102 controls as a reference of the normal response to exercise at altitude. CTEPH patients had a higher New York Health Association (NYHA) functional class than PAH (p = 0.037). There were no differences between patients with PAH and CTEPH in hemodynamics and % of predicted (67.8 18.7 vs. 66.0 19.8, p 0.05), but those with CTEPH had higher dyspnea, VD/VT (0.36 0.09 vs. 0.23 0.9, p 0.001), VE/ (45.8 7.1 vs. 39.3 5.6, p 0.001), and (19.9 7.6 vs. 13.5 7.6, p 0.001) than PAH patients. At altitude, patients with PH present severe alterations in gas exchange during exercise. There were no differences in exercise capacity between PAH and CTEPH, but patients with CTEPH had more dyspnea and greater alterations in gas exchange during exercise. CPET made it possible to identify alterations related to the pathophysiology of CTEPH that could explain the functional class and dyspnea in these patients.

Role of lung ultrasonography for diagnosing atelectasis in robotic pelvic surgeries

Patients undergoing robotic pelvic surgery were included in prospective observational study, they are at increased risk of atelectasis and postoperative pulmonary complications.Lung ultrasonography in basal six zones and arterial gas analysis was performed as baseline after induction of GA and on de-docking robotic arms to detect incidence and severity of atelectasis and its effect on arterial oxygenation.Total fifty patients were recruited in the study with age 61.88 ± 8.49 years, BMI 25.97±4.03, intraoperative with steep trendelenburg position, average duration of docking was 155.32 ± 47.44 minutes, VCV provided to 29 and PCV to 21 patients. [Lung aeration score 0] was noted for all patients in Right anterior basal –Zone I, 50-60% of patients developed mild atelectasis [Lung Aeration score1] in Posterior basal zones III and VI. Total 10% patients developed moderate atelectasis [Lung Aeration score 2] and 4% developed severe atelectasis [Lung Aeration score 3] in zones III and VI. The incidence and severity of atelectasis was not affected by duration of robotic arms docking and mode of ventilation. For both VCV and PCV group statistically significant (p>0.05) decrease in Arterial Oxygen Pressure (Pao2) and Alveolar-arterial (A-a)o gradient difference was detected after completion of robotic surgery compared to baselines values. Atelectasis was detected in 60% patients in bilateral basal posterior zones in patients undergoing robotic pelvic surgeries causing statistically significant decrease in PaO2 compared to baseline values. Early detection of atelectasis by Lung Ultrasonography in the OR and applying optimal PEEP is recommended.

Structural features and thermodynamic properties of Pr0.5Ba0.25Sr0.25MnO3–δ

The structure, oxygen non-stoichiometry, defect equilibrium, and thermodynamic properties of perovskite-type Pr0.5Ba0.25Sr0.25MnO3–δ manganite were studied. It was shown that the manganite can be air synthesized in one step at 1450 °C. Though having a disordered arrangement of Pr, Ba, and Sr atoms, the compound crystallizes with a tetragonal structure (S.G. I4/mcm) due to the regular tilts of MnO6 octahedra. The oxygen content in oxide as a function of oxygen partial pressure and temperature was measured by coulometric titration, and the data were used for the modeling of defect equilibrium. The oxygen content measurements show stability of the manganite at 973–1223 K and oxygen pressure decrease down to 10−16–10−12 atm. The equilibration of defects in Pr0.5Ba0.25Sr0.25MnO3-δ involves oxygen exchange with the gaseous ambient, intrinsic electron excitation, and oxygen disordering reactions. According to thermodynamic calculations, oxygen sites available for oxygen exchange are characterized by praseodymium-rich coordination. The disordering caused by the half substitution of barium by strontium leads to a lower energy of chemical bonding of the labile oxygen in Pr0.5Ba0.25Sr0.25MnO3–δ compared to the parent Pr0.5Ba0.5MnO3–δ manganite.

Influence of hypobaric hypoxic conditions on ocular structure and biological function at high attitudes: a narrative review.

With the development of science and technology, high-altitude environments, involving aviation, aerospace, and mountainous regions, have become the main areas for human exploration, while such complex environments can lead to rapid decreases in air and oxygen pressure. Although modern aircrafts have pressurized cabins and support equipment that allow passengers and crew to breathe normally, flight crew still face repeated exposure to hypobaric and hypoxic conditions. The eye is a sensory organ of the visual system that responds to light and oxygen plays a key role in the maintenance of normal visual function. Acute hypoxia changes ocular structure and function, such as the blood flow rate, and can cause retinal ischemia. We reviewed researches, and summarized them briefly in a review. The acute hypobaric hypoxia affects corneal, anterior chamber angle and depth, pupils, crystal lens, vitreous body, and retina in structure; moreover, the acute hypoxia does obvious effect on visual function; for example, vision, intraocular pressure, oculometric features and dynamic visual performance, visual field, contrast sensitivity, and color perception. We summarized the changes in the physiological structure and function of the eye in hypoxic conditions and to provide a biological basis for the response of the human eye at high-altitude.

Defect-Induced, Ferroelectric-Like Switching and Adjustable Dielectric Tunability in Antiferroelectrics.

Antiferroelectrics, which undergo a field-induced phase transition to ferroelectric order that manifests as double-hysteresis polarization switching, exhibit great potential for dielectric, electromechanical, and electrothermal applications. Compared to their ferroelectric cousins, however, considerably fewer efforts have been made to understand and control antiferroelectrics. Here, it is demonstrated that the polarization switching behavior of an antiferroelectric can be strongly influenced and effectively regulated by point defects. In films of the canonical antiferroelectric PbZrO3 , decreasing oxygen pressure during deposition (and thus increasing adatom kinetic energy) causes unexpected "ferroelectric-like" polarization switching although the films remain in the expected antiferroelectric orthorhombic phase. This "ferroelectric-like" switching is correlated with the creation of bombardment-induced point-defect complexes which pin the antiferroelectric-ferroelectric phase boundaries, and thus effectively delay the phase transition under changing field. The effective pinning energy is extracted via temperature-dependent switching-kinetics studies. In turn, by controlling the concentration of defect complexes, the dielectric tunability of the PbZrO3 can be adjusted, including being able to convert between "positive" and "negative" tunability near zero field. This work reveals the important role and strong capability of defects to engineer antiferroelectrics for new performance and functionalities.

Effects of wearing different face masks on cardiopulmonary performance at rest and exercise in a partially double-blinded randomized cross-over study

The use of face masks became mandatory during SARS-CoV-2 pandemic. Wearing masks may lead to complaints about laboured breathing and stress. The influence of different masks on cardiopulmonary performance was investigated in a partially double-blinded randomized cross-over design. Forty subjects (19–65 years) underwent body plethysmography, ergometry, cardiopulmonary exercise test and a 4-h wearing period without a mask, with a surgical mask (SM), a community mask (CM), and an FFP2 respirator (FFP2). Cardiopulmonary, physical, capnometric, and blood gas related parameters were recorded. Breathing resistance and work of breathing were significantly increased while wearing a mask. During exercise the increase in minute ventilation tended to be lower and breathing time was significantly longer with mask than without mask. Wearing a mask caused significant minimal decreases in blood oxygen pressure, oxygen saturation, an initial increase in blood and inspiratory carbon dioxide pressure, and a higher perceived physical exertion and temperature and humidity behind the mask under very heavy exercise. All effects were stronger when wearing an FFP2. Wearing face masks at rest and under exercise, changed breathing patterns in the sense of physiological compensation without representing a health risk. Wearing a mask for 4-h during light work had no effect on blood gases.

HIF-1 ACTIVATION AND INFLAMMATORY RESPONSES TO HYPOXIA

Acute hypoxia is a significant physiological danger during high-altitude flying and military aircraft missions. The human brain requires a constant supply of oxygen to function properly, and is susceptible to settings with low availability of air oxygen. Hypoxia can influence inflammatory signalling, and both central and systemic responses can activate HIF pathway genes. HIFs are critical molecules that regulate inflammation andhypoxia, ensuring appropriate cell function and survival. Hypoxia is the condition in which insufficient oxygen reaches the body's tissues. It can be caused by a decrease in partial oxygen pressure (PO2) in the environment, problems with breathing and/or oxygen transport, or the inability of tissues to utilise oxygen. Different organs are hypoxic due to differences in tissue oxygen tensions, which are determined by differences in aerobic metabolism. Extremely hypoxic individuals have the most dramatic systemic and neurological adaptations to persistent hypoxia. In this review, we provide an overview of central and systemic responses to hypoxia and discuss the activation of HIF-1 pathway.

Malondialdehyde and carbonyl levels in skeletal muscle tissues after intermittent hypobaric hypoxia exposures

Background: Hypobaric hypoxia is a state of decreased oxygen pressure at high altitudes that can lead to hypoxia and oxidative stress as a result. Skeletal muscle is one of the important organs that can be affected by oxidative stress and cause contractile dysfunction.
 Objective: This study aimed to evaluate the impact of intermittent hypobaric hypoxia on oxidative stress markers in rat skeletal muscle, by measuring malondialdehyde (MDA) and carbonyl levels.
 Methods: Twenty-five Wistar rats were allocated into five groups, including one control group and four hypoxic groups (I-IV). The hypoxic groups were exposed to an altitude of 25,000 feet for 5 minutes using hypobaric chamber in once (I), twice (II), three (III), and four (IV) times, with a 7-day interval period between exposures. The control group remained in normobaric conditions throughout the study. MDA levels were measured by thiobarbituric acid (TBA) test, while carbonyl levels were measured using 2,4-dinitrophenylhydrazine (DNPH) reagent.
 Results: The MDA level was significantly increased in group I compared to the control group (p=0.008). There were decreasing MDA levels in groups II, III, and IV compared to group I. The carbonyl level was significantly higher in group I than the control group (p=0.000), with an even higher level observed in group II. Although the carbonyl levels tended to decrease in groups III and IV, they still remained higher than those of the control group.
 Conclusion: Exposure to hypobaric hypoxia leads to an increase in MDA and carbonyl levels in the skeletal muscles, indicating an elevation of oxidative stress levels. However, the subsequent intermittent hypobaric hypoxia exposure resulted in a reduction in these levels, implying that skeletal muscles may adapt to hypoxic conditions.

The Effects of Antioxidant Consumption on Inflammation and Muscle Soreness at Moderate Altitude in Collegiate Football Student-Athletes

Introduction: Athletics training and competition is associated with increased oxidative stress and inflammation, especially at moderate altitude. This results from an increased formation of reactive oxygen species due to increased metabolic activity of working cells and tissues as well as decreased oxygen pressure. The oxidative stress can cause inflammation and delayed onset muscle soreness (DOMS), which can be a serious problem for athletes training and competing at a high caliber, as it interferes with optimal sport performance and recovery. A diet intervention was developed to study the relationship between antioxidant-rich food consumption and implications per reduced inflammation and DOMS among athletes. Methods: During summer 2021, 32 NCAA Division 1 collegiate football student-athletes living and training at moderate altitude were recruited to participate in a seven-week nutrition intervention. Participants were assigned to either an intervention or control group. Participants in the intervention group consumed at least 10,000 Oxygen Radical Absorbance Capacity (ORAC) score units per day through an antioxidant-rich trail mix constructed by the research team. Participants consumed this trail mix in addition to their normal diet. Participants in the control group did not receive trail mix and continued their normal diet. Inflammation was measured pre- and post- intervention through blood biomarkers (high sensitivity C-reactive protein, hs-CRP; Interleukin-6, IL-6) and urine sample analysis (Isoprostane Creatinine ratio, F2/C). DOMS was measured through a pre- and post- survey (Numerical Pain Rating Scale, NPRS). Results: An independent samples T-test identified the change in mean ORAC scores for the intervention group (M±SD, 149121 units ± 18357 units) was statistically higher than the change in mean ORAC score for the control group (28391 units ± 15359 units): t(30)=-20.02, p<.001. Paired samples T-tests indicated that hs-CRP and F2/C did not change significantly between time 1 (hsCRP: 1.31 mg/dL ±1.28 mg/dL) (F2/C: 0.41 ± 0.23) and time 2 (hsCRP: 1.50 mg/dL ± 1.92 mg/dL) (F2/C: 0.42 ± 0.11). Separate regression analyses identified pre- F2/C as a significant predictor of post- F2/C for the control group (B=0.399, p<0.001) and mean ORAC score as a significant predictor of post- F2/C for the intervention group (B=-3.604E-6, p=0.028). Repeated measures ANOVA indicated no significant effect of time (F(1,27)=0.399, p=.533), or group by time (F(1,27)=0.521, p=.477) on DOMS. Conclusions: Antioxidant-rich food consumption had minimal impact on inflammation or DOMS induced by physical exercise at moderate altitude among this sample of collegiate football student-athletes. Future research is required to assess the relationship between antioxidant consumption and implications per reduced inflammation and DOMS for student-athletes participating in other collegiate sports.

CuInO2 epitaxial thin films on epi-GaN wafer: Fabrication and solar-blind photodetector

High-quality p-type CuInO2 epitaxial thin films with a bandgap of ∼3.99 eV were grown on epitaxial GaN (001) (epi-GaN) wafers by using pulsed laser deposition technology. At a constant growth temperature of 750 °C, the quality of the CuInO2 thin film increases with the decrease in oxygen pressure within the range of 0.09–1 Pa. For the single crystal film obtained at 0.09 Pa, the epitaxial relationship between the film and the substrate is determined to be CuInO2 (001) || GaN (001) with CuInO2 〈100〉 || GaN [100]. The self-powered ultraviolet photodetector prepared based on the highest quality film shows high photoresponsivity 0.31 mA/W and fast response speed (rise time: 0.34 s, decay time: 0.34 s) at zero voltage under 254-nm UV-light, meaning good solar-blind photoresponsivity.

Modeling the oxygen transport to the myocardium at maximal exercise at high altitude.

Exposure to high altitude induces a decrease in oxygen pressure and saturation in the arterial blood, which is aggravated by exercise. Heart rate (HR) at maximal exercise decreases when altitude increases in prolonged exposure to hypoxia. We developed a simple model of myocardial oxygenation in order to demonstrate that the observed blunting of maximal HR at high altitude is necessary for the maintenance of a normal myocardial oxygenation. Using data from the available scientific literature, we estimated the myocardial venous oxygen pressure and saturation at maximal exercise in two conditions: (1) with actual values of maximal HR (decreasing with altitude); (2) with sea‐level values of maximal heart rate, whatever the altitude (no change in HR). We demonstrated that, in the absence of autoregulation of maximal HR, myocardial tissue oxygenation would be incompatible with life above 6200 m–7600 m, depending on the hypothesis concerning a possible increase in coronary reserve (increase in coronary blood flow at exercise). The decrease in maximal HR at high altitude could be explained by several biological mechanisms involving the autonomic nervous system and its receptors on myocytes. These experimental and clinical observations support the hypothesis that there exists an integrated system at the cellular level, which protects the myocardium from a hazardous disequilibrium between O2 supply and O2 consumption at high altitude.

The endocrine kidney: tampering with oxygen sensors may change your character

The endocrine kidney: tampering with oxygen sensors may change your character

The Participation of the Organism Adaptation Mechanisms to the Lack of Oxygen According to the Assessment of the Fethemoglobin Content in the Peripheral Blood of Patients with Community-acquired Pneumonia

Introduction. Сommunity-acquired pneumonia (COP) is a global socio-medical problem. At emergence of pneumonia by any genesis, hypoxia develops. Oxygen homeostasis of the body is provided by the coordinated interaction of external respiration, circulatory system and oxygen-transport system of the blood. Hypoxia, due to the malfunction of the external respiratory system, causes the formation of compensatory changes, in the implementation of which involved components of the oxygen transport system. Molecular genetic mechanisms play an important role in the body's adaptation to oxygen deficiency. Fetal hemoglobin (FetHb), having an increased affinity for oxygen, makes a significant contribution to the body's adaptation to new conditions with altered gaseous environment in the presence of pathological processes occurring with hypoxia. In this regard, it is interest to determine FetHb in adults with COP to study its effect on the diagnosis, prognosis and outcome of the disease. The aim of the study. To determinate the participation of the organism adaptation mechanisms to the lack of oxygen according to the assessment of the content of fetal hemoglobin in the peripheral blood of patients with community-acquired pneumonia. Materials and methods. We examined 34 adult patients (18 women and 16 men) with COP, aged 18 to 80 years, who were in the therapeutic department of the City Clinical Hospital № 25 in Kharkiv. The control group was formed of 20 healthy individuals. Spirography was performed on the diagnostic complex "Valenta"; hematological examinations – on the analyzer "ADVIA 60"; measurement of pO2 and pCO2, oxygen saturation, content of fetal hemoglobin – on the device "RAPIDLAB865". Results. In patients with community-acquired pneumonia, there was a decrease of the ventilatory function of external respiration, which is confirmed by a marked decrease in partial oxygen pressure. Oxygen saturation of blood was reduced in the group of patients with COP, but the difference was not statistically significant 94.8 ± 1.0 %. This indicates the presence of compensatory mechanisms aimed at maintaining adequate blood oxygen saturation. Significant increase in pH (from 7.40 to 7.53) and decrease in standard bicarbonate (from 1.27 to 0.68 mmol/l) resulting from violation of the gas composition of the blood can be regarded as a manifestation of partially compensated respiratory alkalosis. In patients with COP, there was a reduction in the total time of hemolysis, a shift of the maximum erythrogram to the left and an increase in the maximum itself, indicating a sharp decline in erythrocyte resistance. The proportion of erythrocytes with reduced resistance was twice as large as similar forms in the control group and the number of highly resistant cells in patients with COP sharply decreased. Obviously, oxygen starvation-mediated stress erythropoiesis is accompanied by the entry into the circulation of functionally defective erythrocytes. They are subject to accelerated elimination from the vascular bed, which causes a decrease in the quantitative indicators of red blood (erythrocyte content, hemoglobin) while maintaining corpuscular parameters (Mean Corpuscular Volume, Mean Cell Hemoglobin Concentration). At the same time, the analysis of individual hemoglobin fractions revealed an increase in the proportion of fetal hemoglobin (from 2.90 ± 0.31 % in the group of healthy individuals to 5.43 ± 1.05 % in patients with COP) (p less than 0.05). Conclusions. Changes in the parameters of acid hemolysis, fetal hemoglobin in the peripheral blood of patients with community-acquired pneumonia with impaired pulmonary ventilation function indicate their participation in the mechanisms of adaptation to oxygen deficiency and they have informative potential. Elevated fetal hemoglobin in peripheral blood in these patients can be used as an indicator of hypoxia, accompanied by impaired oxygen delivery to tissues, which should be used as an additional criterion for diagnosing tissue hypoxia and justify the timely appointment of antihypoxia drugs. Keywords: hypoxia, community-acquired pneumonia, red blood cells, fetal hemoglobin.

Association Between Severe Chronic Obstructive Pulmonary Disease and Polyneuropathy.

BackgroundChronic obstructive pulmonary disease (COPD) is a life-threatening and devastating disease associated with low-grade systemic inflammation. In adults, the most common disease of the peripheral nervous system is peripheral neuropathy. While most polyneuropathy has a mixed presentation, some cases are motor dominant and others are sensory dominant. We investigated polyneuropathy in patients with COPD and hypothesized that low-grade systemic inflammation and other pathologies in patients with COPD cause peripheral axonal polyneuropathy.Material/MethodsWe included 62 patients with COPD without any neurological signs or symptoms, and 30 healthy volunteers with no known neurological or pulmonary diseases as controls. There were 38 men in the COPD group and 17 men in the control group; the mean ages of the 2 groups were 64.88 and 62.7 years, respectively. According to the Global Initiative for Chronic Obstructive Lung Disease COPD report, all COPD patients were group D. After collecting demographic and clinical characteristics of the participants, we performed an electrophysiological examination to investigate polyneuropathy and pulmonary function test results. C-reactive protein, hemoglobin, creatinine, partial carbon dioxide pressure (pCO2) levels were recorded. Electrophysiological examination was performed with a Medelec Synergy device using standard neurographic procedures, and the results were assessed.ResultsSignificant differences were found for forced expiratory volume in 1 sec (FEV1), %FEV1, forced vital capacity (FVC), %FVC, pCO2, and hemoglobin and creatinine levels, but all participants had a creatinine level within the normal range. There was no difference in sensory neuropathy between the groups, but a significant difference was found in terms of motor neuropathy.ConclusionsAs noted in previous studies, systemic inflammation, increased oxidative stress, decreased oxygen pressure, and multiple comorbidities in patients with COPD may all contribute to the development of neuropathy.

Stable high power deep-uv enhancement cavity in ultra-high vacuum with fluoride coatings.

We demonstrate the superior performance of dielectric fluoride coatings versus oxide coatings in long term vacuum operation of a high power deep-ultraviolet enhancement cavity. In ultra-high vacuum (10-8 mbar), the fluoride optics can maintain up to 10 W of stable intracavity power on one hour time scales, a record-high at these vacuum levels, whereas for the oxide optics, we observe rapid degradation at lower intracavity powers with a rate that increases with power. After observing degradation in high vacuum, we can recover the fluoride and oxide optics with oxygen; however, this recovery process becomes ineffective after several applications. For the fluoride optics, we see that initial UV conditioning in an oxygen environment helps to improve the performances of the optics. In oxygen-rich environments from ∼10-4 mbar, the fluoride optics can stably maintain up to 20 W of intracavity power on several-hour time scales whereas for the oxide optics there is immediate degradation with a rate that increases with decreasing oxygen pressure.

Fuzzy C-Means Clustering with Minkowski and Euclidean Distance for Cerebral Infarction Classification

Cerebral infarction is a condition in which the death of neuronal cells, glial cells and blood vessel system is caused by a lack of oxygen and nutrients. The cause of nerve damage is hypoxia, which is a decrease in oxygen pressure in the alveoli which can cause hypoxemia in brain tissue. Cerebral infarction can also be caused by obstruction of blood flow to the brain so that the brain does not get enough oxygen. This situation is called ischemia. The initial stage of ischemic neurons is characterized by the formation of micro vacuolization, which is characterized by cell size that is still normal or slightly reduced, vacuoles occur in the perikaryon area, which can be found in neurons in the hippocampus and cortical 5-15 minutes after hypoxia. The final sign of cell damage due to ischemia is the nucleus which becomes pyknotic and fragmented. To diagnose the presence or absence of cerebral infarction in the brain it is not enough just to use a CT scan, therefore machine learning will also be used to diagnose the presence or absence of cerebral infarction in the brain. For this reason, the authors propose Fuzzy C-Means Clustering with Minkowski and Euclidean Distance as a classification method that has good accuracy, good precision, good memory, and a good F1-score in calcifying patients whose brains experience infarction or not. In this proposed method, Fuzzy C-Means Clustering with Minkowski and Euclidean Distance is a modification of the Fuzzy C-Means Clustering Algorithm. This modification is proposed to increase the detection capacity of Fuzzy C-Means Clustering. The parameterized Minkowski distance metric is adjusted for implementation with FCM with various settings. The experimental results show that this method can improve the results of the FCM grouping with an accuracy of around 88%.

Epitaxial growth of ε-(AlGa)2O3 films on sapphire substrate by PLD and the fabrication of photodetectors

Pure phase ε-(AlGa)2O3 films were deposited utilizing pulsed laser deposition (PLD) on a sapphire (0001) substrate under the assistance of tin element. High resolution X-ray diffraction (HRXRD) reveals the presence of out-of-plane compressive strain in ε-(AlGa)2O3 films. From XPS and TEM measurements, an increase in oxygen pressure causes a reduction in Al content and a rise in the film growth rate. Moreover, the ε-(AlGa)2O3 films achieve a wider bandgap with a decrease in oxygen pressure, determined by the transmittance spectra and responsivity. For oxygen pressure increasing from 0.006mbar to 0.01mbar and 0.03mbar, the responsivity of the MSM photodetectors are 0.86A/W, 1.87A/W, and 4.38A/W, and an external quantum efficiency (EQE) of 448%, 946%, and 2114%, respectively, indicating larger gains in ε-(AlGa)2O3 devices.

High temperature cyclic oxidation behavior of a low manganese Fe12Mn9Cr5Si4Ni-NbC shape memory stainless steels

High amounts of Mn in Fe-Mn-Si-Cr-Ni shape memory stainless steels are detrimental for oxidation resistance at high temperatures. However, in order to maintain the shape memory effect of these alloys the content of manganese must be between 12 and 19 wt%. Thus, this study evaluated an alloy with relative low Mn (12 wt%) in cyclic oxidation tests at 800, 900 and 1000 °C. Kinetic analysis demonstrated parabolic oxidation behavior with rate similar to higher Mn-containing alloys from literature. It was also observed internal oxidation, for the first time in these alloys, and oxide layers composed by Mn2O3 and Mn-Cr spinel at 800 °C as well as Mn-Cr spinel and no continuous silica at 1000 °C. The internal oxidation mechanism was related to oxide layer defects and not to partial oxygen pressure decrease, considering that the internal oxidation presented the same oxides of the external layer. These results show that low Mn content does not improve the use viability of these alloys at high temperatures, since no decreasing in oxidation rate was observed and further internal oxidation occurred.

Microstructure, optical, and photoluminescence properties of β-Ga2O3 films prepared by pulsed laser deposition under different oxygen partial pressures* *Project supported by the Guizhou Provincial Science and Technology Planning Project, China (Grant No. 2018-5781), the National Natural Science Foundation of China (Grant No. 51762010), the Guizhou Provincial Science and Technology Foundation, China (Grant Nos. 2020-1Y021 and 2020-1Y271), and the Guizhou Provincial

The β-Ga2O3 films are prepared on polished Al2O3 (0001) substrates by pulsed laser deposition at different oxygen partial pressures. The influence of oxygen partial pressure on crystal structure, surface morphology, thickness, optical properties, and photoluminescence properties are studied by x-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), spectrophotometer, and spectrofluorometer. The results of x-ray diffraction and atomic force microscope indicate that with the decrease of oxygen pressure, the full width at half maximum (FWHM) and grain size increase. With the increase of oxygen pressure, the thickness of the films first increases and then decreases. The room-temperature UV-visible (UV-Vis) absorption spectra show that the bandgap of the β-Ga2O3 film increases from 4.76 eV to 4.91 eV as oxygen pressure decreasing. Room temperature photoluminescence spectra reveal that the emission band can be divided into four Gaussian bands centered at about 310 nm (∼ 4.0 eV), 360 nm (∼ 3.44 eV), 445 nm (∼ 2.79 eV), and 467 nm (∼ 2.66 eV), respectively. In addition, the total photoluminescence intensity decreases with oxygen pressure increasing, and it is found that the two UV bands are related to self-trapped holes (STHs) at O1 sites and between two O2-s sites, respectively, and the two blue bands originate from at Ga1 tetrahedral sites. The photoluminescence mechanism of the films is also discussed. These results will lay a foundation for investigating the Ga2O3 film-based electronic devices.