THz Generation in Laser-Induced Breakdown in Carbon Dioxide at Different Levels of Gas Pressure

2020 ◽  
Vol 10 (1) ◽  
pp. 85-92
Author(s):  
Anatoly V. Andreev ◽  
Andrey A. Angeluts ◽  
Alexei V. Balakin ◽  
Igor A. Kotelnikov ◽  
Nikita V. Minaev ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Gas Pressure ◽  
Thz Generation ◽  
Laser Induced Breakdown ◽  
Different Levels

Deep Learning Associated with Laser-Induced Breakdown Spectroscopy (LIBS) for the Prediction of Lead in Soil

2019 ◽  
Vol 73 (5) ◽  
pp. 565-573 ◽  
Author(s):  
Yun Zhao ◽  
Mahamed Lamine Guindo ◽  
Xing Xu ◽  
Miao Sun ◽  
Jiyu Peng ◽  
...  
Keyword(s):  
Deep Learning ◽  
Confusion Matrix ◽  
Principal Component ◽  
Classification Performance ◽  
Soil Samples ◽  
Laser Induced Breakdown Spectroscopy ◽  
Support Vector ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Different Levels

In this study, a method based on laser-induced breakdown spectroscopy (LIBS) was developed to detect soil contaminated with Pb. Different levels of Pb were added to soil samples in which tobacco was planted over a period of two to four weeks. Principal component analysis and deep learning with a deep belief network (DBN) were implemented to classify the LIBS data. The robustness of the method was verified through a comparison with the results of a support vector machine and partial least squares discriminant analysis. A confusion matrix of the different algorithms shows that the DBN achieved satisfactory classification performance on all samples of contaminated soil. In terms of classification, the proposed method performed better on samples contaminated for four weeks than on those contaminated for two weeks. The results show that LIBS can be used with deep learning for the detection of heavy metals in soil.

Understanding Carbon Dioxide Transfer in Direct Methanol Fuel Cells Using a Pore-Scale Model

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Nathaniel Metzger ◽  
Archana Sekar ◽  
Jun Li ◽  
Xianglin Li
Keyword(s):  
Carbon Dioxide ◽  
Pressure Drop ◽  
Gas Flow ◽  
Direct Methanol Fuel Cells ◽  
Gas Pressure ◽  
Mass Transfer Resistance ◽  
Transfer Resistance ◽  
Cell Components ◽  
Direct Methanol ◽  
Methanol Fuel Cells

Abstract The gas flow of carbon dioxide from the catalyst layer (CL) through the microporous layer (MPL) and gas diffusion layer (GDL) has great impacts on the water and fuel management in direct methanol fuel cells (DMFCs). This work has developed a liquid–vapor two-phase model considering the counter flow of carbon dioxide gas, methanol, and water liquid solution in porous electrodes of DMFC. The model simulation includes the capillary pressure as well as the pressure drop due to flow resistance through the fuel cell components. The pressure drop of carbon dioxide flow is found to be about two to three orders of magnitude higher than the pressure drop of the liquid flow. The big difference between liquid and gas pressure drops can be explained by two reasons: volume flowrate of gas is three orders of magnitude higher than that of liquid; only a small fraction of pores (<5%) in hydrophilic fuel cell components are available for gas flow. Model results indicate that the gas pressure and the mass transfer resistance of liquid and gas are more sensitive to the pore size distribution than the thickness of porous components. To buildup high gas pressure and high mass transfer resistance of liquid, the MPL and CL should avoid micro-cracks during manufacture. Distributions of pore size and wettability of the GDL and MPL have been designed to reduce the methanol crossover and improve fuel efficiency. The model results provide design guidance to obtain superior DMFC performance using highly concentrated methanol solutions or even pure methanol.

scholarly journals UK neonatal resuscitation survey

2018 ◽  
Vol 104 (3) ◽  
pp. F324-F325 ◽  
Author(s):  
Elinor Charles ◽  
Katie Hunt ◽  
Vadivelam Murthy ◽  
Christopher Harris ◽  
Anne Greenough
Keyword(s):  
Carbon Dioxide ◽  
Clinical Practice ◽  
Neonatal Resuscitation ◽  
Neonatal Care ◽  
Initial Resuscitation ◽  
Carbon Dioxide Monitoring ◽  
Different Levels

BackgroundPrevious surveys have demonstrated that neonatal resuscitation practices on the delivery suite vary between UK units, particularly according to the hospital’s neonatal unit’s level. Our aim was to determine if recent changes to the Resuscitation Council guidelines had influenced clinical practice.MethodsSurveys of resuscitation practices at UK delivery units carried out in 2012 and 2017 were compared.ResultsComparing 2017 with 2012, initial resuscitation using air was more commonly used in both term (98% vs 75%, p<0.001) and preterm (84% vs 34%, p<0.001) born infants. Exhaled carbon dioxide monitoring was more frequently employed in 2017 (84% vs 19%, p<0.001). There were no statistically significant differences in practices according to the level of neonatal care provided by the hospital.ConclusionThere have been significant changes in neonatal resuscitation practices in the delivery suite since 2012 regardless of the different levels of neonatal care offered.

Remarkable Activity of Nanoarchitectonics Mesoporous CuO/CeO2–TiO2 Prepared by Nanocasting and Deposition Precipitation Techniques

2020 ◽  
Vol 20 (5) ◽  
pp. 2791-2802
Author(s):  
Duangamol Ongmali ◽  
Sakollapath Pithakratanayothin ◽  
Sureerat Jampa ◽  
Apanee Luengnaruemitrchai ◽  
Thanyalak Chaisuwan ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Crystallite Size ◽  
Oxygen Vacancies ◽  
Redox Properties ◽  
Oxygen Defect ◽  
Nitrate Salt ◽  
Hard Template ◽  
Different Levels

In this work, a ceria (CeO2) support was modified with titania (TiO2) by nanocasting using MCM-48 as a hard template and then loading Cu (as the nitrate salt) at different levels (3–9% by weight) by deposition-precipitation followed by calcination. The addition of TiO2 in MSP CeO2 revealed that the MSP CeO2 was significantly improved the oxygen vacancies of the catalyst by increasing the Ce3+ content from 38 to 75% and stabilizing the Ce3+ species by bonding with the oxygen as Ce(4f)-O(2p)-Ti(3d). Moreover, the bonding of MSP CeO2 with TiO2 generated the oxygen defect vacancies (s–Ti3+), allowing Cu2+ to occupy and be reduced to Cu+ during calcination. The smaller CeO2 crystallite size (2.7 nm) of 9Cu/CeO2–TiO2 increased the mass-specific CO-Oxidation, showing the best catalytic activity due to its highest redox properties, as determined by H2-TPR and also showing resistant property to water and carbon dioxide. Indeed, water was adsorbed on the Ce3+ sites, generating OHads which reacted with CO to form –COOH, resulting in CO2.

The concentration and pressure dependent diffusion of carbon dioxide in nitrile rubbers

1992 ◽  
Vol 339 (1655) ◽  
pp. 497-519 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Diffusion Coefficient ◽  
High Pressures ◽  
Ambient Pressure ◽  
Weight Fraction ◽  
Gas Pressure ◽  
Time Dependent ◽  
Initial Increase ◽  
Parametric Function ◽  
Ambient Gas

The paper reports the results of an experimental and associated analytical study of the time dependent adsorption of carbon dioxide gas into two nitrile elastomers. The mass gas sorption has been measured using a device based on a vibrating reed to a weight fraction accuracy of ca . 0.05 % at 47 °C in the ambient gas pressure range 0.1-34 MPa. The experimental method is described and data are provided. These data are used to compute the most effective description of the diffusion process by invoking a number of different diffusion coefficient, D(θ), characteristics, where θ denotes lapsed time, ambient pressure and local ambient gas concentration within the elastomers. The numerical procedures adopted to perform the fitting of the experimental data with various D(θ) characteristics are described and the quality of the fit is assessed. The D(θ) characteristics chosen have no particular physical basis but follow established empirical precedents. The characteristics of the parameters associated with the various D(θ) functions generally indicate that as the gas is embibed with progressively increasing ambient pressures the diffusion coefficient increases. At high pressures the diffusion is arrested and the coefficient decreases. We have associated the initial increase with gas induced plasticization and the eventual decreases with the effect of the hydrostatic component of the ambient gas pressure. The parameter fitting also indicates that the diffusion is arrested with lapsed time which is tentatively associated with time dependent volumetric relaxations. These interpretations apart, the data and analyses clearly indicate that the transport is not simply fickian and a relatively complex parametric function to describe the sensitivity of the diffusion coefficient to time, concentration and pressure is necessary for these systems.

scholarly journals A Method for the Measurement of Carbon Dioxide Desorption from Coal in the Elevated Pressure Range

1996 ◽  
Vol 13 (2) ◽  
pp. 71-84 ◽  
Author(s):  
Adam Nodzeński
Keyword(s):  
Carbon Dioxide ◽  
Heat Exchange ◽  
Pressure Range ◽  
Elevated Pressure ◽  
Gas Pressure ◽  
Coal Bed ◽  
Empirical Equations ◽  
Grain Sizes ◽  
Gas Desorption ◽  
Endothermic Process

During the liberation of gas from a coal bed, the temperature of the system is decreased because desorption is an endothermic process and heat exchange with the surroundings is difficult. A method for measuring gas desorption in the elevated pressure range, enabling investigations under isothermal and quasi-adiabatic conditions, was described. The results of carbon dioxide desorption from Polish coal were presented. The study was carried out using different rates of decrease in the external gas pressure for different coal grain sizes. The non-isothermal desorption curves thus obtained were described using empirical equations. Extrapolation of the equation constants obtained enabled the desorption curves to be calculated for the limit of decrease in rate of the external gas pressure and of grain size. It was found experimentally that the dependence of the decrease in coal temperature on the amount of desorbed gas is linear provided that heat exchange with the surroundings is limited.

scholarly journals Conduction of heat through powders and its dependence on the pressure and conductivity of the gaseous phase

1926 ◽  
Vol 113 (764) ◽  
pp. 459-477 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Thermal Conductivity ◽  
Gaseous Phase ◽  
Linear Relation ◽  
Gas Pressure ◽  
Pumice Stone ◽  
Solid Part ◽  
Thermal Conductivities

The object of our investigation has been to study the conduction of heat through a light powder and to find how it depends upon the pressure and thermal conductivity of the gas in which the powder is immersed. A solution of this question is part of the solution of the problem of the conduction of heat through a certain class of “solid” heat insulators—a class which includes those of lowest thermal conductivity. The class of insulator referred to are solids dispersed in gases, or gases dispersed in solids, and consists of three kinds of substances, (1) fibrous substances ( e.g., wool, eiderdown, asbestos), (2) cellular substances (e. g., cork, pumice stone) and (3) powders (e. g., lamp-black, powdered cork, silox or monox). It might be expected that substances so different as those mentioned would have very different thermal conductivities. Actually their conductivities range from about 8 to 11 times 10 -5 cal. cm. -1 deg. -1 sec. -1 . As there is nothing common to the solid part of these substances, their conductivities, it would seem probable, are determined mainly by the factor which is common to them all, that is, the gaseous part, which is air. Our experiments have been made with a very light powder known as monox or silox, and the conductivity of this powder when immersed in air, in carbon dioxide, and in hydrogen at various pressures has been determined. We find that there is a linear relation between the conductivity of the powder and the logarithm of the pressure of the gas in which it is immersed, so that if k is the measure of the conductivity of the powder, k 0 that of the gas in which it is immersed, and p the measure of the gas pressure, then k = ½ k 0 log 10 p/n approximately, where n is a constant for a given gas.

scholarly journals Changes in Optic Nerve Sheath Diameter in Response to Various Levels of End-Tidal Carbon Dioxide in Healthy Patients under General Anesthesia

2018 ◽  
Vol 05 (02) ◽  
pp. 94-97
Author(s):  
Indu Kapoor ◽  
Ankur Khandelwal ◽  
Charu Mahajan ◽  
Hemanshu Prabhakar ◽  
Parmod Kumar Bithal
Keyword(s):  
Carbon Dioxide ◽  
Optic Nerve ◽  
General Anesthesia ◽  
Optic Nerve Sheath Diameter ◽  
Nerve Sheath ◽  
End Tidal Carbon Dioxide ◽  
Two Measures ◽  
The Difference ◽  
End Tidal ◽  
Different Levels

Abstract Background Intracranial pressure (ICP) monitoring is an essential component in management of traumatic brain-injured (TBI) patients. While invasive techniques are associated with many complications, noninvasive nature of ultrasonographic measurement of optic nerve sheath diameter (ONSD) is now becoming popular. Carbon dioxide (CO2) alters the ICP by changing the size of cerebral vasculature. We aimed to assess the effect of (hypercarbia and hypocarbia) different levels of end-tidal carbon dioxide (EtCO2) on ONSD. Methods Thirty adult patients aged between 18 and 65 years, undergoing brachial plexus injury surgery under general anesthesia, were enrolled. Following standard anesthetic protocol, ONSD was measured at different time points of EtCO2. ONSD was measured at EtCO2 of 40 and then 30 mm Hg to assess change in ONSD due to hypocarbia (Thypocarbia). Similarly, ONSD was measured at EtCO2 of 50 mm Hg to assess change in ONSD due to hypercarbia (Thypercarbia). The mean of three ONSD values at each time point was taken as the final value. The generalized estimating equation (GEE) was used to analyze correlation between different levels of EtCO2 and ONSD. Results The calculated 95% confidence interval (CI) for the difference of two measures (Thypocarbia, EtCO2 40 and 30 mm Hg) on ONSD was −0.056 to −0.036, and the calculated CI for the difference of other two measures (Thypercarbia, EtCO2 40 and 50 mm Hg) on ONSD was 0.044 to 0.077, and thus were observed to be significant. Conclusions ONSD changes significantly in response to different EtCO2 levels in healthy non-neurosurgical patients under general anesthesia.

Sign in / Sign up

Export Citation Format

Share Document