Reactions of SiCl groups in amorphous SiO2 with mobile interstitial chemical species: Formation of interstitial Cl2 and HCl molecules, and role of interstitial H2O molecules

2005 ◽  
Vol 98 (4) ◽  
pp. 043515 ◽  
Author(s):  
Koichi Kajihara ◽  
Masahiro Hirano ◽  
Linards Skuja ◽  
Hideo Hosono
Keyword(s):  
Chemical Species ◽  
Amorphous Sio2 ◽  
Species Formation

3D simulations of warm and hot Jupiter atmospheres: the role of 3D mixing in shaping CH4-to-CO conversion pathways

2021 ◽  
Author(s):  
Maria Zamyatina ◽  
Eric Hebrard ◽  
Nathan Mayne ◽  
Benjamin Drummond
Keyword(s):  
Chemical Structure ◽  
Three Dimensional ◽  
Chemical Species ◽  
Radiation Chemistry ◽  
3D Simulations ◽  
Horizontal Advection ◽  
Co Conversion ◽  
Area Of Influence ◽  
Different Parts

<p>We present results from a set of cloud-free simulations of exoplanet atmospheres using a coupled three-dimensional (3D) hydrodynamics-radiation-chemistry model. We report in particular our investigation of the thermodynamic and chemical structure of the atmospheres of HAT-P-11b and WASP-17b and their comparison with the results for the atmospheres of HD 189733b and HD 209458b presented in Drummond et al. (2020). We found that the abundances of chemical species from simulations with interactive chemistry depart from their respective abundances computed at local chemical equilibrium, especially at higher latitudes. To understand this departure, we analysed the CH<sub>4</sub>-to-CO conversion pathways within the Venot et al. (2019) reduced chemical network used in our model using a chemical network analysis. We found that at steady state nine CH<sub>4</sub>-to-CO conversion pathways manifest in our 3D simulations with interactive chemistry, with different pathways dominating different parts of the atmosphere and their area of influence being determined by the vertical and horizontal advection and shifting between planets.</p>

scholarly journals The Role of Oxidative Stress in Cardiac Disease: From Physiological Response to Injury Factor

2020 ◽  
Vol 2020 ◽  
pp. 1-29 ◽  
Author(s):  
Rossella D’Oria ◽  
Rossella Schipani ◽  
Anna Leonardini ◽  
Annalisa Natalicchio ◽  
Sebastio Perrini ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Myocardial Injury ◽  
Antioxidant Defense ◽  
Experimental Studies ◽  
Chemical Species ◽  
Oxygen Species ◽  
Molecular Abnormalities ◽  
Defense Systems ◽  
Antioxidant Defense Systems

Reactive oxygen species (ROS) are highly reactive chemical species containing oxygen, controlled by both enzymatic and nonenzymatic antioxidant defense systems. In the heart, ROS play an important role in cell homeostasis, by modulating cell proliferation, differentiation, and excitation-contraction coupling. Oxidative stress occurs when ROS production exceeds the buffering capacity of the antioxidant defense systems, leading to cellular and molecular abnormalities, ultimately resulting in cardiac dysfunction. In this review, we will discuss the physiological sources of ROS in the heart, the mechanisms of oxidative stress-related myocardial injury, and the implications of experimental studies and clinical trials with antioxidant therapies in cardiovascular diseases.

scholarly journals Characterization of a boreal convective boundary layer and its impact on atmospheric chemistry during HUMPPA-COPEC-2010

2012 ◽  
Vol 12 (19) ◽  
pp. 9335-9353 ◽  
Author(s):  
H. G. Ouwersloot ◽  
J. Vilà-Guerau de Arellano ◽  
A. C. Nölscher ◽  
M. C. Krol ◽  
L. N. Ganzeveld ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Chemistry ◽  
Convective Boundary Layer ◽  
Large Scale ◽  
Spatial Scales ◽  
Potential Temperature ◽  
Chemical Species ◽  
Convective Boundary ◽  
The Impact

Abstract. We studied the atmospheric boundary layer (ABL) dynamics and the impact on atmospheric chemistry during the HUMPPA-COPEC-2010 campaign. We used vertical profiles of potential temperature and specific moisture, obtained from 132 radio soundings, to determine the main boundary layer characteristics during the campaign. We propose a classification according to several main ABL prototypes. Further, we performed a case study of a single day, focusing on the convective boundary layer, to analyse the influence of the dynamics on the chemical evolution of the ABL. We used a mixed layer model, initialized and constrained by observations. In particular, we investigated the role of large scale atmospheric dynamics (subsidence and advection) on the ABL development and the evolution of chemical species concentrations. We find that, if the large scale forcings are taken into account, the ABL dynamics are represented satisfactorily. Subsequently, we studied the impact of mixing with a residual layer aloft during the morning transition on atmospheric chemistry. The time evolution of NOx and O3 concentrations, including morning peaks, can be explained and accurately simulated by incorporating the transition of the ABL dynamics from night to day. We demonstrate the importance of the ABL height evolution for the representation of atmospheric chemistry. Our findings underscore the need to couple the dynamics and chemistry at different spatial scales (from turbulence to mesoscale) in chemistry-transport models and in the interpretation of observational data.

scholarly journals Homoploid hybrid speciation and genome evolution via chromosome sorting

2015 ◽  
Vol 282 (1807) ◽  
pp. 20150157 ◽  
Author(s):  
Vladimir A. Lukhtanov ◽  
Nazar A. Shapoval ◽  
Boris A. Anokhin ◽  
Alsu F. Saifitdinova ◽  
Valentina G. Kuznetsova
Keyword(s):  
Reproductive Isolation ◽  
Direct Consequence ◽  
Convincing Evidence ◽  
Interspecific Crosses ◽  
Parental Origin ◽  
Hybrid Speciation ◽  
Species Formation ◽  
Homoploid Hybrid ◽  
Creative Role

Genomes of numerous diploid plant and animal species possess traces of interspecific crosses, and many researches consider them as support for homoploid hybrid speciation (HHS), a process by which a new reproductively isolated species arises through hybridization and combination of parts of the parental genomes, but without an increase in ploidy. However, convincing evidence for a creative role of hybridization in the origin of reproductive isolation between hybrid and parental forms is extremely limited. Here, through studying Agrodiaetus butterflies, we provide proof of a previously unknown mode of HHS based on the formation of post-zygotic reproductive isolation via hybridization of chromosomally divergent parental species and subsequent fixation of a novel combination of chromosome fusions/fissions in hybrid descendants. We show that meiotic segregation, operating in the hybrid lineage, resulted in the formation of a new diploid genome, drastically rearranged in terms of chromosome number. We also demonstrate that during the heterozygous stage of the hybrid species formation, recombination was limited between rearranged chromosomes of different parental origin, representing evidence that the reproductive isolation was a direct consequence of hybridization.

scholarly journals The role of meiotic drive in hybrid male sterility

2010 ◽  
Vol 365 (1544) ◽  
pp. 1265-1272 ◽  
Author(s):  
Shannon R. McDermott ◽  
Mohamed A. F. Noor
Keyword(s):  
Male Sterility ◽  
Hybrid Sterility ◽  
Meiotic Drive ◽  
Mechanistic Explanation ◽  
Hybrid Progeny ◽  
Hybrid Male ◽  
Hybrid Male Sterility ◽  
Species Formation ◽  
Allelic Segregation

Meiotic drive causes the distortion of allelic segregation away from Mendelian expected ratios, often also reducing fecundity and favouring the evolution of drive suppressors. If different species evolve distinct drive-suppressor systems, then hybrid progeny may be sterile as a result of negative interactions of these systems' components. Although the hypothesis that meiotic drive may contribute to hybrid sterility, and thus species formation, fell out of favour early in the 1990s, recent results showing an association between drive and sterility have resurrected this previously controversial idea. Here, we review the different forms of meiotic drive and their possible roles in speciation. We discuss the recent empirical evidence for a link between drive and hybrid male sterility, also suggesting a possible mechanistic explanation for this link in the context of chromatin remodelling. Finally, we revisit the population genetics of drive that allow it to contribute to speciation.

Fundamental Role of Creation and Activation in Radiation-Induced Defect Production in High-Purity Amorphous SiO2

1996 ◽  
Vol 76 (16) ◽  
pp. 2926-2929 ◽  
Author(s):  
V. A. Mashkov ◽  
Wm. R. Austin ◽  
Lin Zhang ◽  
R. G. Leisure
Keyword(s):  
High Purity ◽  
Defect Production ◽  
Amorphous Sio2 ◽  
Radiation Induced
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