scholarly journals Chemical Composition in the Envelopes of Different WR Subtypes

1991 ◽  
Vol 143 ◽  
pp. 75-80 ◽  
Author(s):  
T. Nugis
Keyword(s):  
Chemical Composition ◽  
Reaction Rate ◽  
Energy Levels ◽  
Statistical Equilibrium ◽  
Equilibrium Equations ◽  
Line Intensities ◽  
Independent Information ◽  
Theoretical Line ◽  
Model Independent ◽  
The Mean

Valuable model-independent information about the chemical composition of WR stars can be obtained by using lines of different ions arising at transitions between highly excited energy levels. We determine the abundances of He, H, C, N, O using theoretical line intensities obtained by solving statistical equilibrium equations for level populations for different subtype WR envelope conditions.The chemical composition of WR stars strongly differs from the mean cosmic composition. In the case of WN stars nuclear processed CNO products of H-burning are revealed in the envelopes and He-burning products in the WC envelopes.The abundance of oxygen in WC stars differs from the predictions of recent evolutionary calculations which account for the new 12C(α,γ) 16O reaction rate.

scholarly journals The Chemical Composition of the Wolf-Rayet Envelopes

1991 ◽  
Vol 145 ◽  
pp. 209-220
Author(s):  
T. Nugis
Keyword(s):  
Chemical Composition ◽  
Energy Levels ◽  
Independent Information ◽  
Model Independent ◽  
The Mean ◽  
Ring Nebulae

Model-independent information on the chemical composition of WR stars is obtained from the lines of different ions arising at transitions between highly excited energy levels.The chemical composition of WR stars strongly differs from the mean cosmic composition. Nuclear processed CNO products of H-burning are revealed in WN envelopes and He-burning products in WC envelopes. The matter enriched with He and N is also present in some ring nebulae around WN stars.

scholarly journals Emissivities of Fe III and Fe VI and Iron Abundances in Planetary Nebulae

1978 ◽  
Vol 76 ◽  
pp. 159-160
Author(s):  
R.H. Garstang ◽  
W. Derek Robb
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Planetary Nebulae ◽  
Statistical Equilibrium ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Equilibrium Equations ◽  
Line Intensities ◽  
Astrophysical Journal ◽  
Excitation Cross Sections

We have calculated electron impact excitation cross sections between most of the low metastable levels of the 3d6 configuration in Fe III and of the 3d3 configuration in Fe VI have also been computed. The statistical equilibrium equations have been solved for a range of electron temperatures and electron densities, and the resulting level populations used to calculate emissivities for the forbidden lines of Fe III and Fe VI. Comparisons with observed line intensities and abundance determinations in planetary nebulae are in progress. (Paper submitted to The Astrophysical Journal.)

MASERS: A Python package for statistical equilibrium calculations applied to masers

2017 ◽  
Vol 13 (S336) ◽  
pp. 13-16
Author(s):  
R. van Rooyen ◽  
D. J. van der Walt
Keyword(s):  
Chemical Composition ◽  
Open Source ◽  
Energy Levels ◽  
Matrix Inversion ◽  
Statistical Equilibrium ◽  
Escape Probability ◽  
Physical Conditions ◽  
Equilibrium Calculations ◽  
Python Package ◽  
Inversion Calculation

AbstractThe study of astrophysical maser formation provides a useful probe of the chemical composition and physical conditions of the sources they are observed in. This exploration requires continuously solving the SE equations for the populations of the energy levels in search of conditions that will produce an inversion. After evaluation of available implementations applying the Escape Probability approximation, the masers solver was developed to provide an efficient and robust matrix inversion calculation. This open source package is hosted at https://bitbucket.org/ruby_van_rooyen/masers.

On the Inhomogeneity of Chemical Composition over the Surface of 21 Per

1976 ◽  
Vol 32 ◽  
pp. 343-349
Author(s):  
Yu.V. Glagolevsky ◽  
K.I. Kozlova ◽  
V.S. Lebedev ◽  
N.S. Polosukhina
Keyword(s):  
Chemical Composition ◽  
Spectral Line ◽  
Variable Star ◽  
Radial Velocities ◽  
Crimean Astrophysical Observatory ◽  
Line Intensities ◽  
Magnetic Variable

SummaryThe magnetic variable star 21 Per has been studied from 4 and 8 Å/mm spectra obtained with the 2.6 - meter reflector of the Crimean Astrophysical Observatory. Spectral line intensities (Wλ) and radial velocities (Vr) have been measured.

Influence of the sex and type of tissue on the basic chemical composition and the content of minerals in the sirloin and offal of fattener pigs

2019 ◽  
Vol 99 (2) ◽  
pp. 343-348 ◽  
Author(s):  
Marek Babicz ◽  
Anna Kasprzyk ◽  
Kinga Kropiwiec-Domańska
Keyword(s):  
Chemical Composition ◽  
Mineral Content ◽  
Cadmium Concentration ◽  
Pork Meat ◽  
Threshold Values ◽  
Large White ◽  
Sodium Calcium ◽  
Mineral Components ◽  
Longissimus Lumborum ◽  
The Mean

The aim of the study was to determine the basic chemical composition and mineral content in the sirloin and offal of fattener pigs, taking their sex into consideration. In addition, comparative analysis of the content of chemical and mineral components in the sirloin and offal was performed. The experimental material included 24 crossbred (Polish Landrace × Polish Large White) fatteners, from which samples of sirloin (musculus longissimus lumborum), liver, heart, and kidneys were collected for the analysis. A significant effect of the sex on the fat content in the sirloin and liver and on the level of magnesium (Mg), zinc, and iron (Fe) in the sirloin was demonstrated. Significant differences were found in the basic chemical composition and mineral content between the sirloin and the offal. In comparison with the liver, the sirloin contained lower amounts of protein and fat and higher potassium and Mg contents. In turn, the offal was shown to be a rich source of sodium, calcium, and trace elements (Fe, manganese, and copper). The mean cadmium concentration in the sirloin and offal was significantly lower than the threshold values for these elements, i.e., it accounted for 26% and 6.2% (liver)–19.5% (heart) of the allowable content of this element in pork meat and offal.

Volumes of activation for electrode processes of various charge-types in nonaqueous solvents

2001 ◽  
Vol 79 (12) ◽  
pp. 1864-1869 ◽  
Author(s):  
Mitsuru Matsumoto ◽  
Delanie Lamprecht ◽  
Michael R North ◽  
Thomas W Swaddle
Keyword(s):  
Electron Transfer ◽  
Reaction Rate ◽  
Electrode Reaction ◽  
State Theory ◽  
Exchange Reactions ◽  
Pt Electrode ◽  
Electrode Processes ◽  
Solvent Dynamics ◽  
The Mean ◽  
Dynamical Control

Volumes of activation (ΔV‡el) are reported for electron transfer at a Pt electrode of Mn(CN-cyclo-C6H11)62+/+ in acetonitrile, acetone, methanol, and propylene carbonate, and of Fe(phen)33+/2+ in acetonitrile. In all cases, ΔV‡el is markedly positive, whereas for the homogeneous self-exchange reactions of these couples in the same solvents the corresponding parameter is known to be strongly negative. The rate constants for the electrode reactions correlate loosely with the mean reactant diffusion coefficients (i.e., with solvent fluidity) and the ΔV‡el values with the volumes of activation for diffusion (i.e., for viscous flow), consistent with solvent dynamical control of the electrode reaction rate in organic solvents. A detailed analysis of ΔV‡el values of the kind presented for a couple with an uncharged member (Zhou and Swaddle, Can. J. Chem. 79, 841 (2001)) fails, however, either because of ion-pairing effects with these more highly charged couples or because of breakdown of transition-state theory in predicting the contribution of the activational barrier. Attempts to measure ΔV‡el for the oxidation of the uncharged molecule ferrocene at various electrodes in acetonitrile were unsuccessful, although ΔV‡el was again seen to be clearly positive.Key words: electrode kinetics, volumes of activation, nonaqueous electron transfer, solvent dynamics.

scholarly journals Modern quantitative microstructure analysis on the example of aicu5mg1 alloys

2002 ◽  
pp. 109-114
Author(s):  
Biljana Zlaticanin ◽  
Branislav Radonjic ◽  
Branka Jordovic
Keyword(s):  
Grain Size ◽  
Chemical Composition ◽  
Linear Method ◽  
Titanium Content ◽  
Mean Value ◽  
Grain Refining ◽  
Relative Standard ◽  
Method Of Measurement ◽  
The Mean ◽  
Picture Analysis

Using an automatic, QUANTIMET 500 MC, device for quantitative picture analysis and applying linear method of measurement on the example of AlCu5Mg1 alloys, the grain size (min, max and medium values), as well as relative standard measuring errors (RSE), dendrite arm spacing (DAS) and length eutectic (Le) and also distribution by size (histogram) and volume participation of ?-hard solution and eutectic have been determined. We have also studied the influence of grain-refining additives AlTi5B1 for the same chemical composition of the aluminium-capper-magnesium alloy. It has been concluded that with the increase of titanium content, the mean value of grain size decreases. We have also examined hardness and pressure strength.

scholarly journals Effects of longitudinal short-distance constraints on the hadronic light-by-light contribution to the muon $$\mathbf {g-2}$$

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Jan Lüdtke ◽  
Massimiliano Procura
Keyword(s):  
Short Distance ◽  
Independent Method ◽  
Recent Model ◽  
Low Energy ◽  
Muon Anomalous Magnetic Moment ◽  
Distance Constraints ◽  
Independent Information ◽  
Intermediate States ◽  
Model Independent ◽  
Interpolation Functions

AbstractWe present a model-independent method to estimate the effects of short-distance constraints (SDCs) on the hadronic light-by-light contribution to the muon anomalous magnetic moment $$a_\mu ^\text {HLbL}$$ a μ HLbL . The relevant loop integral is evaluated using multi-parameter families of interpolation functions, which satisfy by construction all constraints derived from general principles and smoothly connect the low-energy region with those where either two or all three independent photon virtualities become large. In agreement with other recent model-based analyses, we find that the SDCs and thus the infinite towers of heavy intermediate states that are responsible for saturating them have a rather small effect on $$a_\mu ^\text {HLbL}$$ a μ HLbL . Taking as input the known ground-state pseudoscalar pole contributions, we obtain that the longitudinal SDCs increase $$a_\mu ^\text {HLbL}$$ a μ HLbL by $$(9.1\pm 5.0) \times 10^{-11}$$ ( 9.1 ± 5.0 ) × 10 - 11 , where the isovector channel is responsible for $$(2.6\pm 1.5) \times 10^{-11}$$ ( 2.6 ± 1.5 ) × 10 - 11 . More precise estimates can be obtained with our method as soon as further accurate, model-independent information about important low-energy contributions from hadronic states with masses up to 1–2 GeV become available.

scholarly journals Twenty years of observations of PM 1-188: Its chemical abundances and extraordinary kinematics

2021 ◽  
Author(s):  
Miriam Peña ◽  
Liliana Hernández-Martínez ◽  
Francisco Ruiz-Escobedo
Keyword(s):  
Chemical Composition ◽  
Planetary Nebula ◽  
Central Star ◽  
Emission Lines ◽  
Type I ◽  
Chemical Abundances ◽  
Line Intensities ◽  
Physical Conditions ◽  
The Past ◽  
Spectrophotometric Data

Abstract The analysis of 20 years of spectrophotometric data of the double shell planetary nebula PM 1-188 is presented, aiming to determine the time evolution of the emission lines and the physical conditions of the nebula, as a consequence of the systematic fading of its [WC 10] central star whose brightness has declined by about 10 mag in the past 40 years. Our main results include that the [O iii], [O ii], [N ii] line intensities are increasing with time in the inner nebula as a consequence of an increase in electron temperature from 11 000 K in 2005 to more than 14 000 K in 2018, due to shocks. The intensity of the same lines are decreasing in the outer nebula, due to a decrease in temperature, from 13 000 K to 7000 K, in the same period. The chemical composition of the inner and outer shells was derived and they are similar. Both nebulae present subsolar O, S and Ar abundances, while they are He, N and Ne rich. For the outer nebula the values are 12+log He/H = 11.13 ± 0.05, 12+log O/H = 8.04 ± 0.04, 12+log N/H = 7.87 ± 0.06, 12+log S/H = 7.18 ± 0.10 and 12+log Ar = 5.33 ± 0.16. The O, S and Ar abundances are several times lower than the average values found in disc non-Type I PNe, and are reminiscent of some halo PNe. From high resolution spectra, an outflow in the N-S direction was found in the inner zone. Position-velocity diagrams show that the outflow expands at velocities in the −150 to 100 km s−1 range, and both shells have expansion velocities of about 40 km s−1.

Efficacy of Hounsfield Unit of CT in Prediction of the Chemical Composition of Urinary Stones

QJM ◽  
2021 ◽  
Vol 114 (Supplement_1) ◽  
Author(s):  
Ahmed Salah Mahmoud Ahmed Shehata ◽  
Mohamed Rafik El-Halaby ◽  
Ahmed Mohamed Saafan
Keyword(s):  
Uric Acid ◽  
Chemical Composition ◽  
Calcium Phosphate ◽  
Calcium Oxalate ◽  
Chemical Structure ◽  
Urinary Calculi ◽  
Hounsfield Unit ◽  
Urinary Stones ◽  
The Mean ◽  
Struvite Stones

Abstract Objectives to make a reliable correlation between the chemical composition of the urinary calculi and its Hounsfield unit on CT scan, upon which we can depend on it for prediction of the type of the urinary calculi. The prediction of the chemical structure of the stone would help us to reach a more efficient therapeutic and prophylactic plan. Methods A retrospective study was performed by interpretation of the preoperative CT scans for patients who were presented by urinary stones. Identification of the chemical structure of the calculi was implemented using Fourier Transform Infrared Spectroscopy (FT-IR spectroscopy). The laboratory report revealed multiple types of stones either of pure or mixed composition. Afterwards, a comparison was done between Hounsfield units of the stones and the chemical structure. Results The chemical structure of the urinary stones revealed four pure types of stones (Uric acid, Calcium Oxalate, Struvite and Cystine) and two types of mixed stones (mixed calcium oxalate+ Uric, and mixed calcium oxalate+ calcium phosphate). Uric acid stone had a mean Hounsfield Unit (HU) density of428 ± 81, which was quite less than the other stones, followed by struvite stones with density ranging about 714 ± 38. Mixed calcium oxalate stones could be differentiated from other types of stones like uric acid, pure calcium oxalate and struvite stones by the Hounsfield unit of Computed Tomography (the mean Hounsfield Unit was 886 ± 139 and 1427 ± 152 for mixed calcium oxalate + uric stone and mixed calcium oxalate + calcium phosphate stones respectively). Moreover, pure calcium oxalate stones were easily differentiated from all other stones using the mean Hounsfield density as it was 1158 ± 83. It was challenging only when it was compared to cystine stones, as they were quiet similar to HU value (997 ± 14). The variation of Hounsfield values among the previously mentioned stones, was statistically significant (p < 0.001). Conclusion The study proved that the Hounsfield Unit of CT scanning is a convenient measure to predict the chemical structure of urinary calculi.

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