scholarly journals Unveiling the physical and chemical conditions in the young disk around L1527

2017 ◽  
Vol 13 (S332) ◽  
pp. 121-123
Author(s):  
M. L. R. van ’t Hoff ◽  
J. J. Tobin ◽  
D. Harsono ◽  
E. F. van Dishoeck
Keyword(s):  
Spatial Distribution ◽  
Chemical Structure ◽  
Protoplanetary Disks ◽  
Young Stars ◽  
Kinetic Temperature ◽  
Temperature Structure ◽  
Chemical Conditions ◽  
Embedded Disks ◽  
Physical And Chemical ◽  
Co Emission

AbstractPlanets form in disks around young stars. The planet formation process may start when the protostar and disk are still deeply embedded within their infalling envelope. However, unlike more evolved protoplanetary disks, the physical and chemical structure of these young embedded disks are still poorly constrained. We have analyzed ALMA data for 13CO, C18O and N2D+ to constrain the temperature structure, one of the critical unknowns, in the disk around L1527. The spatial distribution of 13CO and C18O, together with the kinetic temperature derived from the optically thick 13CO emission and the non-detection of N2D+, suggest that this disk is warm enough (≳ 20 K) to prevent CO freeze-out.

scholarly journals UV-controlled physical and chemical structure of protoplanetary disks

2011 ◽  
pp. 33-38
Author(s):  
V. V. Akimkin ◽  
Y. N. Pavlyuchenkov ◽  
A. I. Vasyunin ◽  
D. S. Wiebe ◽  
M. S. Kirsanova ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Protoplanetary Disks ◽  
Physical And Chemical

scholarly journals λ = 2 mm spectroscopy observations toward the circumnuclear disk of NGC 1068

2020 ◽  
Vol 634 ◽  
pp. A125 ◽  
Author(s):  
Jianjie Qiu ◽  
Jiangshui Zhang ◽  
Yong Zhang ◽  
Lanwei Jia ◽  
Xindi Tang
Keyword(s):  
Kinetic Temperature ◽  
Ionization Degree ◽  
Star Forming ◽  
High Ionization ◽  
Frequency Coverage ◽  
Ngc 1068 ◽  
Line Survey ◽  
Circumnuclear Disk ◽  
Chemical Conditions ◽  
Physical And Chemical

Aims. We investigate the physical and chemical conditions of molecular gas in the circumnuclear disk (CND) region of NGC 1068. Methods. We carried out a spectral line survey with the IRAM 30 m telescope toward the center of NGC 1068 and mainly focused on the 2 mm band with a frequency coverage of 160.7–168.6 GHz and 176.5–184.3 GHz. Results. Fifteen lines are detected in NGC 1068, eight of which are new detections for this galaxy. We derive the rotation temperatures and column densities of fourteen molecular species. Conclusions. Based on the [HCO+ (2 − 1)]/[HOC+ (2 − 1)] ratio, we obtain a high ionization degree in the CND of NGC 1068. It is found that HC3N is concentrated in the east knot, while 13CCH, CH3CN, SO, HOC+, CS, CH3CCH, and H2CO are concentrated in the west knot. Compared to the star-forming galaxies M 82 and NGC 253, the chemistry of NGC 1068 might be less strongly affected by the UV radiation field, and its kinetic temperature might be lower.

scholarly journals UV-controlled physical and chemical structure of protoplanetary disks

2011 ◽  
Vol 335 (1) ◽  
pp. 33-38 ◽  
Author(s):  
V. V. Akimkin ◽  
Y. N. Pavlyuchenkov ◽  
A. I. Vasyunin ◽  
D. S. Wiebe ◽  
M. S. Kirsanova ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Protoplanetary Disks ◽  
Physical And Chemical

Resolving star and planet formation with ALMA

2018 ◽  
Vol 14 (S345) ◽  
pp. 106-110
Author(s):  
Per Bjerkeli ◽  
Daniel Harsono ◽  
Matthijs H. D. van der Wiel ◽  
Jon P. Ramsey ◽  
Lars E. Kristensen ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Chemical Structure ◽  
Planet Formation ◽  
Young Stars ◽  
Direct Impact ◽  
Disk Formation ◽  
Disk Structure ◽  
Early Evidence ◽  
First Results ◽  
Physical And Chemical

AbstractDisks around young stars are the sites of planet formation. As such, the physical and chemical structure of disks have a direct impact on the formation of planetary bodies. Outflowing winds remove angular momentum and mass and affect the disk structure and therefore potentially planet formation. Until very recently, we have lacked the facilities to provide the necessary observational tools to peer into the wind launching and planet forming regions of the young disks. Within the framework of the Resolving star formation with ALMA program, young protostellar systems are targeted with ALMA to resolve the disk formation, outflow launching and planet formation. This contribution presents the first results of the program. The first resolved images of outflow launching from a disk were recently reported towards the Class I source TMC1A (Bjerkeli et al. 2016) where we also present early evidence of grain growth (Harsono et al. 2018).

scholarly journals Safety of Some Synthetic Food Colours: Review

2021 ◽  
Vol 9 (12) ◽  
pp. 2347-2354
Author(s):  
Abdalla S. Ammar ◽  
Mennat Allah I. Atwa ◽  
Dorreya M. Faress ◽  
Ashgan M. Ali
Keyword(s):  
United States Of America ◽  
Chemical Structure ◽  
Food Additives ◽  
Daily Intake ◽  
Food Colorants ◽  
Production Technologies ◽  
Chemical Conditions ◽  
Artificial Food Colors ◽  
Physical And Chemical ◽  
Food Colours

Food additives are used to protect food, increase quality and extend shelf life in many stages, from production to consumption of food. Colorants added by food producers to color food or to adjust the color to desired level are among the commonly used food additives. Considering today's developing production technologies, foods fade or discolor at various stages of processing, storage, and sale due to physical and chemical conditions such as heat, light, pH and oxygen. Colorants are used to regain these color losses, to enhance weak colors, to give color to the food that is actually colorless, and to win back the favour of customers by hiding low quality. Therefore, the most used food colorants in Canada, China, European Union, Mexico and United States of America were presented. The chemical name, chemical structure, common uses, acceptable daily intake (ADI), and toxicity literature of six most used artificial food colors were reviewed.

Permeability to albumin in isolated coronary venules

1993 ◽  
Vol 265 (2) ◽  
pp. H543-H552 ◽  
Author(s):  
Y. Yuan ◽  
W. M. Chilian ◽  
H. J. Granger ◽  
D. C. Zawieja
Keyword(s):  
Permeability Coefficient ◽  
Filtration Rate ◽  
Intraluminal Pressure ◽  
Apparent Permeability ◽  
Filtration Pressure ◽  
Diffusive Permeability ◽  
Apparent Permeability Coefficient ◽  
Chemical Conditions ◽  
Physical And Chemical ◽  
Intravascular Pressure

This study reports measurements of albumin permeability in isolated coronary venules. The isolated microvessel technique allows the quantification of transmural exchange of macromolecules under tightly controlled physical and chemical conditions. Transvenular exchange of albumin was studied in isolated coronary venules during alterations in filtration rate caused by changes in intravascular pressure. The apparent permeability coefficient of albumin (Pa) at an intraluminal pressure of 11 cmH2O was 3.92 +/- 0.43 x 10(-6) cm/s. Elevating intraluminal pressure to 16 and 21 cmH2O increased Pa to 5.13 +/- 0.57 x 10(-6) and 6.78 +/- 0.66 x 10(-6) cm/s, respectively. Calculation of the true diffusive permeability coefficient of albumin (Pd) at zero filtration rate was 1.54 x 10(-6) cm/s. The product of hydraulic conductance (Lp) and (1 - sigma), where sigma is the solute reflection coefficient, was 3.25 x 10(-7) cm.s-1 x cmH2O-1. At a net filtration pressure of 4-5 cmH2O, diffusion accounts for > 60% of total albumin transport across the venular wall. Transmural albumin flux is very sensitive to filtration rate, rising 6.7% for each cmH2O elevation of net filtration pressure. At 11 cmH2O net filtration pressure, convection accounts for nearly 70% of net albumin extravasation from the venular lumen. We suggest that the isolated coronary venule is a suitable preparation for the study of solute exchange in the heart.

scholarly journals Effects of Various Types of Expandable Graphite and Blackcurrant Pomace on the Properties of Viscoelastic Polyurethane Foams

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1801
Author(s):  
Rafał Oliwa ◽  
Joanna Ryszkowska ◽  
Mariusz Oleksy ◽  
Monika Auguścik-Królikowska ◽  
Małgorzata Gzik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Structure ◽  
Oxygen Index ◽  
Polyurethane Foams ◽  
Expandable Graphite ◽  
Ftir Analysis ◽  
Limiting Oxygen Index ◽  
Peak Heat Release Rate ◽  
Physical And Chemical ◽  
Scanning Electron

We investigated the effect of the type and amount of expandable graphite (EG) and blackcurrant pomace (BCP) on the flammability, thermal stability, mechanical properties, physical, and chemical structure of viscoelastic polyurethane foams (VEF). For this purpose, the polyurethane foams containing EG, BCP, and EG with BCP were obtained. The content of EG varied in the range of 3–15 per hundred polyols (php), while the BCP content was 30 php. Based on the obtained results, it was found that the additional introduction of BCPs into EG-containing composites allows for an additive effect in improving the functional properties of viscoelastic polyurethane foams. As a result, the composite containing 30 php of BCP and 15 php of EG with the largest particle size and expanded volume shows the largest change in the studied parameters (hardness (H) = 2.65 kPa (+16.2%), limiting oxygen index (LOI) = 26% (+44.4%), and peak heat release rate (pHRR) = 15.5 kW/m2 (−87.4%)). In addition, this composite was characterized by the highest char yield (m600 = 17.9% (+44.1%)). In turn, the change in mechanical properties is related to a change in the physical and chemical structure of the foams as indicated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis.

scholarly journals Origin of Life on Mars: Suitability and Opportunities

Life ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 539
Author(s):  
Benton C. Clark ◽  
Vera M. Kolb ◽  
Andrew Steele ◽  
Christopher H. House ◽  
Nina L. Lanza ◽  
...  
Keyword(s):  
Origin Of Life ◽  
Energy Sources ◽  
Early Earth ◽  
Sediment Samples ◽  
Life On Mars ◽  
Eventual Return ◽  
History Of ◽  
Early Mars ◽  
Chemical Conditions ◽  
Physical And Chemical

Although the habitability of early Mars is now well established, its suitability for conditions favorable to an independent origin of life (OoL) has been less certain. With continued exploration, evidence has mounted for a widespread diversity of physical and chemical conditions on Mars that mimic those variously hypothesized as settings in which life first arose on Earth. Mars has also provided water, energy sources, CHNOPS elements, critical catalytic transition metal elements, as well as B, Mg, Ca, Na and K, all of which are elements associated with life as we know it. With its highly favorable sulfur abundance and land/ocean ratio, early wet Mars remains a prime candidate for its own OoL, in many respects superior to Earth. The relatively well-preserved ancient surface of planet Mars helps inform the range of possible analogous conditions during the now-obliterated history of early Earth. Continued exploration of Mars also contributes to the understanding of the opportunities for settings enabling an OoL on exoplanets. Favoring geochemical sediment samples for eventual return to Earth will enhance assessments of the likelihood of a Martian OoL.

scholarly journals Probing the 2D temperature structure of protoplanetary disks withHerschelobservations of high-JCO lines

2016 ◽  
Vol 591 ◽  
pp. A95 ◽  
Author(s):  
D. Fedele ◽  
E. F. van Dishoeck ◽  
M. Kama ◽  
S. Bruderer ◽  
M. R. Hogerheijde
Keyword(s):  
Protoplanetary Disks ◽  
Temperature Structure
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