The Important Role of Dissolved Oxygen Supply Regulated by the Hydraulic Shear Force during the Biosynthesis of Iron Hydroxysulfate Minerals

The severity of environmental pollution from acid mine drainage (AMD) is increasingly garnering attention. In this study, the effects of hydraulic shear forces (achieved by regulating the shaking table’s rotation speed) on Fe2+ bio-oxidation and Fe3+ hydrolytic mineralization in an acidic 9K medium-FeSO4-Acidithiobacillus ferrooxidans system (simulated AMD) are investigated. Results reveal that a higher shaking speed favors a higher oxidation rate of Fe2+, whereas a very low or high shaking speed restricts the removal of Fe3+. Shaking table rotation speeds of 120–180 rpm were preferred for biomineralization treatment in the simulated AMD. As the initial concentration of Fe2+ in the system decreased from 9.67 to 0 g/L in 40 h, the dissolved O2 (DO) in the solution dropped to its lowest concentration after 20 h and then increased to its initial level between 40 and 120 h. However, the corresponding total Fe (TFe) precipitation efficiency increased with the increasing mineralization time after 40 h. The effect of O2 supply time on biomineralization revealed that DO was mainly used in Fe2+ bio-oxidation. After Fe2+ was completely oxidized by A. ferrooxidans, the precipitation efficiency of TFe was independent of the O2 supply.

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Role of thromboxane A2 in the control of myocardial O2 supply/consumption balance and severity of ischemia during pacing-induced ischemia.

Circulation Research ◽

10.1161/01.res.64.3.575 ◽

1989 ◽

Vol 64 (3) ◽

pp. 575-582 ◽

Cited By ~ 7

Author(s):

G J Grover ◽

C S Parham

Keyword(s):

Thromboxane A2 ◽

O2 Supply

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THE ROLE OF EFFLORESCENT SULFATES IN THE STORAGE OF TRACE ELEMENTS IN STREAM WATERS POLLUTED BY ACID MINE-DRAINAGE: THE CASE OF PENA DEL HIERRO, SOUTHWESTERN SPAIN

The Canadian Mineralogist ◽

10.2113/gscanmin.44.6.1431 ◽

2006 ◽

Vol 44 (6) ◽

pp. 1431-1446 ◽

Cited By ~ 36

Author(s):

A. Romero ◽

I. Gonzalez ◽

E. Galan

Keyword(s):

Trace Elements ◽

Acid Mine Drainage ◽

Mine Drainage ◽

Acid Mine ◽

Stream Waters

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Role of Beta Adrenoceptors in the Control of Myocardial O2 Supply/Consumption Heterogeneity

Analysis and Simulation of the Cardiac System — Ischemia ◽

10.1201/9781003068341-29 ◽

2020 ◽

pp. 319-332

Author(s):

Harvey R. Weiss ◽

Mary E. Upsher

Keyword(s):

Beta Adrenoceptors ◽

O2 Supply

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Characteristics of physical preparedness of biathlons

Scientific Journal of National Pedagogical Dragomanov University. Series 15. Scientific and pedagogical problems of physical culture (physical culture and sports) ◽

10.31392/npu-nc.series15.2021.4(134).02 ◽

2021 ◽

pp. 9-12

Author(s):

I.O. Asaulyuk ◽

I.I. Buy

Keyword(s):

Physical Fitness ◽

Annual Cycle ◽

Initial Level ◽

Training Process ◽

Foreign Literature ◽

Leading Role ◽

Preparatory Period

Analysis of recent research and publications shows that in domestic and foreign literature are widely represented materials that represent the leading role of physical fitness of biathletes in achieving high sports results, as well as means and methods of its development. The article analyzes the importance of physical fitness in improving the efficiency of the training process of biathletes. Based on the literature, the most significant qualities for biathlon training were identified. The data of the authors are presented, in order to achieve a high sports result the leading role is played by physical fitness, the athlete's performance at the main competitions largely depends on what level of physical fitness he received in the preparatory period of the annual cycle. It is established that in biathlon special endurance occupies the main place in the system of preparation of athletes for participation in competitions. The main goal of the study was to assess the initial level of physical fitness of biathletes in the preparatory period of the annual cycle. Assessment of the level of physical fitness of the subjects was carried out on the sum of points obtained for 5 tests. It was determined that the studied biathletes corresponded to the level of physical fitness "Sufficient". Note that the strength indicators corresponded to the level of "Average", and were at a lower level than other physical qualities. The endurance indicators of the studied biathletes were at the level of "High".

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Radical mechanisms of methyl vinyl ketone oligomerization through aqueous phase OH-oxidation: on the paradoxical role of dissolved molecular oxygen

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-2913-2013 ◽

2013 ◽

Vol 13 (1) ◽

pp. 2913-2954 ◽

Cited By ~ 2

Author(s):

P. Renard ◽

F. Siekmann ◽

A. Gandolfo ◽

J. Socorro ◽

G. Salque ◽

...

Keyword(s):

Aqueous Phase ◽

High Resolution Mass Spectrometry ◽

Organic Aerosol ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Chemical Mechanism ◽

Methyl Vinyl ◽

Phase Chemistry ◽

Dissolved O2

Abstract. It is now accepted that one of the important pathways of Secondary Organic Aerosol (SOA) formation occurs through aqueous phase chemistry in the atmosphere. However, the liquid phase chemical mechanisms leading to macromolecules are still not well understood. For α-dicarbonyl precursors, such as methylglyoxal and glyoxal, radical reactions through OH-oxidation produce oligomers, irreversibly and faster than accretion reactions. Methyl vinyl ketone (MVK) was chosen in the present study as it is an α, β-unsaturated carbonyl that can undergo such reaction pathways in the aqueous phase and forms even high molecular weight oligomers. We present here experiments on the aqueous phase OH-oxidation of MVK, performed under atmospheric relevant conditions. Using NMR and UV absorption spectroscopy, high and ultra-high resolution mass spectrometry, we show that the fast formation of oligomers up to 1800 Da is due to radical oligomerization of MVK, and 13 series of oligomers (out of a total of 26 series) are identified. The influence of atmospherically relevant parameters such as temperature, initial concentrations of MVK and dissolved oxygen are presented and discussed. In agreement with the experimental observations, we propose a chemical mechanism of OH-oxidation of MVK in the aqueous phase that proceeds via radical oligomerization of MVK on the olefin part of the molecule. This mechanism highlights the paradoxical role of dissolved O2: while it inhibits oligomerization reactions, it contributes to produce oligomerization initiator radicals, which rapidly consume O2, thus leading to the supremacy of oligomerization reactions after several minutes of reaction. These processes, together with the large ranges of initial concentrations investigated (60–656 μM of dissolved O2 and 0.2–20 mM of MVK) show the fundamental role that O2 likely plays in atmospheric organic aerosol.

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