Basic Radiological Science
Thomas A. Carder in Handling of Radiation Accident Patients, 1993
An oxygen atom has 2 electrons in its inner of two shells, the K shell, and 6 in the outer shell, the L shell, for a total of 8 electrons, which is okay since oxygen has 8 protons. A hydrogen atom has only one electron shell, the K shell, holding only one electron, which is also okay since the hydrogen atom has only one proton (refer to Section A of Figure 1.9). Recall that the first shell of any atom, the K shell, can hold 2 electrons and the second shell, the L shell, can hold 8 electrons. Notice in Section B of Figure 1.9 that the oxygen atom has 2 electrons in the K shell and 8 in the L shell. That totals 10 electrons. That doesn't seem right! That is too many electrons for oxygen. There are only 8 protons in the nucleus of the oxygen atom. And with 8 protons, the oxygen atom can have only 8 electrons. Right? Not exactly. Remember, the L shell has a capacity of 8 electrons. Granted, with 2 electrons in the K shell of the oxygen atom, the L shell needs only 6 electrons for the oxygen atom to be electrically satisfied. However, that does not prohibit oxygen from containing more than 6 electrons in the L shell. Likewise, each of the two hydrogen atoms needs only 1 electron to be electrically satisfied but the K shell of any atom has a capacity of 2 electrons. How is it then that in Section B of Figure 1.9 there are 8 electrons in the L shell of the oxygen atom? Further, Section B of Figure 1.9 shows actually 2 electrons in the K shell of each hydrogen atom, but the K shell of each hydrogen atom only needs one electron since there is only one proton in each hydrogen atom?
Cardiac catheterization for the adult with complex congenital heart disease
Debabrata Mukherjee, Eric R. Bates, Marco Roffi, Richard A. Lange, David J. Moliterno, Nadia M. Whitehead in Cardiovascular Catheterization and Intervention, 2017
Oximetry can detect shunts and be utilized in the calcula- tion of cardiac output. It is critical to avoid obtaining the data with the patient on oxygen via nasal cannula. The oxy- gen saturation should be obtained from the patient on room air, and it should be drawn from a location distal to the shunt lesion. Oxygen saturation is the percentage of hemo- globin that is present as oxyhemoglobin and is measured by reflectance. Oxygen content is the total amount of oxygen present in the blood. This includes the oxyhemoglobin plus the oxygen dissolved in the plasma. The oxygen content is calculated with the following formula:
Therapeutic Gases for Neurological Disorders
Sahab Uddin, Rashid Mamunur in Advances in Neuropharmacology, 2020
Oxygen (O2) is a colorless, odorless, tasteless, and transparent gas, which combines with all other elements except inert gases to form oxides. It was discovered by the Joseph Priestley of England and Carl Wilhelm Scheele of Germany. It was named as oxygen by Antoine Lavoisier in 1774 (Partington et al., 1989). It is the third most abundant element on the earth and is utilized by the body for oxidation and combustion processes. As a therapeutic gas, it was first experimented on the mouse by the Priestley who reported that the mice were more active and lived longer breathing it (Emsley et al., 2001).
Isolation and identification of three new chromones from the leaves of Pimenta dioica with cytotoxic, oestrogenic and anti-oestrogenic effects
Published in Pharmaceutical Biology, 2018
Brian J. Doyle, Temitope O. Lawal, Tracie D. Locklear, Lorraina Hernandez, Alice L. Perez, Udeshi Patel, Shitalben Patel, Gail B. Mahady
The substitution pattern in the A ring was determined based on HMBC correlations (Figure 1(b)) between both methyl groups and C-7 (δ C 159.4 ppm), suggesting that a hydroxy-substituted carbon, C-7, was positioned between the two methylated carbons, C-6 and C-8. The methyl group assigned to C-6 also correlated with C-5, which was assigned based on HMBC correlation with the hydroxyl proton at δ 13.0 ppm. Furthermore, NMR data for this compound are consistent with previously published NMR data for the 6,8-dimethyl-5,7-dihydroxyflavone syzalterin (Youssef et al. 1998). Also important was the observation that the upshifted carbonyl resonance was indicative of a flavone (double bond between C-2 and C-3), but the downshifted resonances of C-2 and C-1′ did not correspond to a simple flavone structure. Furthermore, the molecular formula derived from HRMS data suggested a sixth oxygen atom. HMBC and HSQC correlations clearly indicated a proton at C-3 rather than the –OH substitution typical of flavonols. Positioning the oxygen atom between C-2 and C-1′ creating a 2-phenoxy moiety results in the observed downshift of C-2 and C-1′ resonances. This is supported by previously published NMR data for the 2-phenoxychromone piliostigmin (Ibewuike et al. 1996).
Review on Chemistry of Oxazole derivatives: Current to Future Therapeutic Prospective
Published in Egyptian Journal of Basic and Applied Sciences, 2023
Sweta Joshi, Meenakshi Mehra, Ramandeep Singh, Satinder Kakar
In 1962 oxazole entity was firstly synthesized, but the chemistry of oxazole established. In past 1876 by synthesizing 2-methyl oxazole. In the beginning of the First World War oxazole entity came into prominence, when penicillin antibiotic was invented. During the invention of dienes in the Diels Alder reaction a new beginning of oxazole chemistry will occur. Oxazole has 3 carbon, 1 nitrogen and 1 oxygen atoms. These all are sp2 hybridized and planar. The atoms also contains unhybridized p orbital which is perpendicular to the plane of σ bonds. Totally six non-bonding electrons are present, out of which 3 are of carbon 1 from nitrogen and 2 of oxygen (Figure 2). So oxygen atom is highly electronegative, thus the delocalization is not overly effective [6].
Magnetic fields and apoptosis: a possible mechanism
Published in Electromagnetic Biology and Medicine, 2022
The spin state plays a pivotal role in all the redox reactions that are at the core of our metabolic machinery. Redox reactions involve the transfer of electrons from one reactant to another. These kinds of reactions are so important that our life depends on them. The synthesis of many complex molecules often requires the oxidation of their precursors, via the use of molecular oxygen. The reason why oxygen is so important in biology is its atomic structure, characterized by the presence of two uncoupled electron spins despite its even atomic number. According to Pauli’s principle, a fundamental principle in quantum physics, oxygen can be considered as an “electron lover,” due to the need of additional electrons to match the coupled spins, in search for stability, thus finally acting as an oxidant. The utilization of molecular oxygen is vital in many biological pathways and the ability of aerobic organisms to harness the power of molecular oxygen as a terminal electron acceptor in their respiratory cycles has revolutionized the evolution of life (Falkowski and Godfrey 2008). The presence of two uncoupled electrons in the oxygen atomic structure makes oxygen a di-radical, since when an electron is uncoupled we are usually dealing with an uncoupled spin or free radical.
Related Knowledge Centers
- Animal
- Chemical Compound
- Chemical Reaction
- Diatomic Molecule
- Helium
- Oxide
- Oxidizing Agent
- Hydrogen
- Standard Temperature & Pressure
- Geological History of Oxygen