The Return of the Exiled Elements

2016 ◽  
Author(s):  
Ben McFarland
Keyword(s):  
Periodic Table ◽  
Chemical Potential ◽  
Comic Book ◽  
Cambrian Explosion ◽  
Signaling Proteins ◽  
Dry Land ◽  
Rocky Slope ◽  
Late Cambrian ◽  
Fast Chemistry ◽  
Set Up

The last page in a comic book is often a cliffhanger, so you’ll be more inclined to buy the next issue. It happens so regularly that as I read through the comic (yes, I still read a comic or two), I find myself trying to anticipate what kind of twist will be on the last page. The best twists are the ones you could have seen coming, but didn’t. The story in this book also has a chemical twist here, near the end. This twist is innovative, expensive, and predictable from chemistry. For this twist, the periodic table plays spoiler. Before the Cambrian explosion, hidden in the nets of signaling proteins within cells and signaling molecules outside cells, the cells held a secret chemical potential that could send a much faster signal, built from four elements involved in two of the balances set up in Chapter 5. This form of signaling would be incredibly expensive, but also incredibly fast. It would be electric in its nature and in its effects, the basis of both muscles and brains. Like water flowing randomly down a rocky slope, this fast signaling built from fast chemistry spread out in many different ways in life. At certain points, evolution came together and converged, repeatedly finding that a particular shape or signal was the best solution to a particular problem. Because the liquid flow of life was increased, it could diverge and converge more quickly, while predictably fitting into the shape of its landscape and efficiently moving downhill. The fast chemistry that forms the basis of fast muscles and faster neurons developed with the Cambrian explosion, along with oxygen and calcium use. The explosion of life provided predators that ate and prey that was eaten. Oxygen’s energy (resulting from its place on the periodic table) allowed more complex food chains, with more predators and more prey. For example, some calculate that more oxygen in the late Cambrian made more predators evolve. In response to this oxygen, certain species moved onto dry land, where they had more contact with that element.

scholarly journals Modular invariance in finite temperature Casimir effect

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Francesco Alessio ◽  
Glenn Barnich
Keyword(s):  
Partition Function ◽  
Chemical Potential ◽  
Casimir Effect ◽  
Temperature Inversion ◽  
Massless Scalar ◽  
Partition Functions ◽  
Parallel Plates ◽  
Modular Transformations ◽  
Real Analytic ◽  
Set Up

Abstract The temperature inversion symmetry of the partition function of the electromagnetic field in the set-up of the Casimir effect is extended to full modular transformations by turning on a purely imaginary chemical potential for adapted spin angular momentum. The extended partition function is expressed in terms of a real analytic Eisenstein series. These results become transparent after explicitly showing equivalence of the partition functions for Maxwell’s theory between perfectly conducting parallel plates and for a massless scalar with periodic boundary conditions.

scholarly journals Flavour effects in gravitational leptogenesis

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Rome Samanta ◽  
Satyabrata Datta
Keyword(s):  
Mass Spectrum ◽  
Chemical Potential ◽  
Mass Scale ◽  
Lepton Number ◽  
Type I ◽  
Lepton Asymmetry ◽  
Seesaw Mechanism ◽  
Set Up ◽  
The Right ◽  
Lepton Number Violating

Abstract Within the Type-I seesaw mechanism, quantum effects of the right-handed (RH) neutrinos in the gravitational background lead to an asymmetric propagation of lepton and anti-leptons which induces a Ricci scalar and neutrino Dirac-Yukawa coupling dependent chemical potential and therefore a lepton asymmetry in equilibrium. At high temperature, lepton number violating scattering processes try to maintain a dynamically generated lepton asymmetry in equilibrium. However, when the temperature drops down, the interactions become weaker, and the asymmetry freezes out. The frozen out asymmetry can act as a pre-existing asymmetry prior to the standard Fukugita-Yanagida leptogenesis phase (Ti ∼ Mi, where Mi is the mass of ith RH neutrino). It is then natural to consider the viability of gravitational leptogenesis for a given RH mass spectrum which is not consistent with successful leptogenesis from decays. Primary threat to this gravity-induced lepton asymmetry to be able to successfully reproduce the observed baryon-to-photon ratio is the lepton number violating washout processes at Ti ∼ Mi. In a minimal seesaw set up with two RH neutrinos, these washout processes are strong enough to erase a pre-existing asymmetry of significant magnitude. We show that when effects of flavour on the washout processes are taken into account, the mechanism opens up the possibility of successful leptogenesis (gravitational) for a mass spectrum M2 » 109GeV » M1 with M1 ≳ 6.3 × 106 GeV. We then briefly discuss how, in general, the mechanism leaves its imprints on the low energy CP phases and absolute light neutrino mass scale.

scholarly journals Decoupled evolution of soft and hard substrate communities during the Cambrian Explosion and Great Ordovician Biodiversification Event

2016 ◽  
Vol 113 (25) ◽  
pp. 6945-6948 ◽  
Author(s):  
Luis A. Buatois ◽  
Maria G. Mángano ◽  
Ricardo A. Olea ◽  
Mark A. Wilson
Keyword(s):  
Late Ordovician ◽  
Hard Substrate ◽  
Cambrian Explosion ◽  
Early Cambrian ◽  
Continuous Increase ◽  
Late Cambrian ◽  
Unconsolidated Sediment ◽  
Underlying Causes ◽  
Hard Substrates ◽  
Shed Light

Contrasts between the Cambrian Explosion (CE) and the Great Ordovician Biodiversification Event (GOBE) have long been recognized. Whereas the vast majority of body plans were established as a result of the CE, taxonomic increases during the GOBE were manifested at lower taxonomic levels. Assessing changes of ichnodiversity and ichnodisparity as a result of these two evolutionary events may shed light on the dynamics of both radiations. The early Cambrian (series 1 and 2) displayed a dramatic increase in ichnodiversity and ichnodisparity in softground communities. In contrast to this evolutionary explosion in bioturbation structures, only a few Cambrian bioerosion structures are known. After the middle to late Cambrian diversity plateau, ichnodiversity in softground communities shows a continuous increase during the Ordovician in both shallow- and deep-marine environments. This Ordovician increase in bioturbation diversity was not paralleled by an equally significant increase in ichnodisparity as it was during the CE. However, hard substrate communities were significantly different during the GOBE, with an increase in ichnodiversity and ichnodisparity. Innovations in macrobioerosion clearly lagged behind animal–substrate interactions in unconsolidated sediment. The underlying causes of this evolutionary decoupling are unclear but may have involved three interrelated factors: (i) a Middle to Late Ordovician increase in available hard substrates for bioerosion, (ii) increased predation, and (iii) higher energetic requirements for bioerosion compared with bioturbation.

scholarly journals Modeling chemical reactions in porous media: a review

2021 ◽  
Vol 33 (6) ◽  
pp. 2279-2300
Author(s):  
Bettina Detmann
Keyword(s):  
Porous Media ◽  
Chemical Reactions ◽  
Chemical Potential ◽  
Mixture Theory ◽  
Reaction Diffusion ◽  
Second Law Of Thermodynamics ◽  
Reaction Diffusion Equations ◽  
Set Up ◽  
The 1960S ◽  
In The Beginning

AbstractFirst, different porous media theories are presented. Some approaches are based on the classical mixture theory for fluids introduced in the 1960s by Truesdell and Coworkers. One of the first researchers who extended the theory to porous media (thus mixtures containing at least one solid constituent) and also accounting for chemical reactions was Bowen. Another important branch of porous media theory goes back to Biot. In the beginning, he dealt with classical geotechnical problems and set up his model empirically. Mathematicians often use reaction–diffusion equations which are limited in comparison with continuum models by several restrictive assumptions and very often only applicable to special problems. In this paper, the focus lies on approaches based on the mixture theory which incorporate chemical reactions. Different strategies to describe the chemical potential for mixtures are presented, and different opinions about the exploitation of the second law of thermodynamics for mixtures are put forward. Finally, several works of different types including chemical reactions in porous media are summarized.

Quantum Mechanics and the Periodic Table

2019 ◽  
Author(s):  
Eric Scerri
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Periodic Table ◽  
Chemical Properties ◽  
Pauli Exclusion Principle ◽  
Niels Bohr ◽  
Exclusion Principle ◽  
Old Quantum Theory ◽  
Set Up ◽  
Three Body

In chapter 7, the influence of the old quantum theory on the periodic system was considered. Although the development of this theory provided a way of reexpressing the periodic table in terms of the number of outer-shell electrons, it did not yield anything essentially new to the understanding of chemistry. Indeed, in several cases, chemists such as Irving Langmuir, J.D. Main Smith, and Charles Bury were able to go further than physicists in assigning electronic configurations, as described in chapter 8, because they were more familiar with the chemical properties of individual elements. Moreover, despite the rhetoric in favor of quantum mechanics that was propagated by Niels Bohr and others, the discovery that hafnium was a transition metal and not a rare earth was not made deductively from the quantum theory. It was essentially a chemical fact that was accommodated in terms of the quantum mechanical understanding of the periodic table. The old quantum theory was quantitatively impotent in the context of the periodic table since it was not possible to even set up the necessary equations to begin to obtain solutions for the atoms with more than one electron. An explanation could be given for the periodic table in terms of numbers of electrons in the outer shells of atoms, but generally only after the fact. But when it came to trying to predict quantitative aspects of atoms, such as the ground-state energy of the helium atom, the old quantum theory was quite hopeless. As one physicist stated, “We should not be surprised . . . even the astronomers have not yet satisfactorily solved the three-body problem in spite of efforts over the centuries.” A succession of the best minds in physics, including Hendrik Kramers, Werner Heisenberg, and Arnold Sommerfeld, made strenuous attempts to calculate the spectrum of helium but to no avail. It was only following the introduction of the Pauli exclusion principle and the development of the new quantum mechanics that Heisenberg succeeded where everyone else had failed.

Elements of Heroism

2019 ◽  
Vol 41 (4) ◽  
pp. 34-37
Author(s):  
Suze Kundu
Keyword(s):  
Science Fiction ◽  
Periodic Table ◽  
Relative Size ◽  
Comic Book ◽  
Chemical Properties ◽  
Relative Reactivity ◽  
Physical And Chemical Properties ◽  
Fiction Writers ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract In today’s periodic table, 118 elements stand side by side, neatly arranged in rows and columns, mapping out their relative size, proudly sharing their family’s traits, and showcasing their relative reactivity and predicted behaviour in different situations. Back in 1869 when Dmitri Mendeleev devised the arrangement of elements we use to this day, there were notable gaps left for elements that had not yet been discovered. As the arrangement of the elements was based on a range of physical and chemical properties, it was easy to predict some of the properties of the missing elements. It was in these gaps that both scientists and artists alike dared to dream about elemental discoveries with both predicted and unpredicted properties. Comic book and science fiction writers in particular had fun postulating some of the possible elements that would give their superheroes the characteristics they required to carry out their tasks. They created fictional elements in place of some of the as yet undiscovered elements, many of which now share properties with elements that exist today.

Nonhydrostatic Stress

1993 ◽  
Author(s):  
Brian Bayly
Keyword(s):  
Normal Stress ◽  
Chemical Potential ◽  
Normal Force ◽  
Tangential Force ◽  
Unit Vector ◽  
Small Areas ◽  
Left Handedness ◽  
Principal Directions ◽  
Unit Of Length ◽  
Set Up

As in the chapters on chemical potential, it will again be assumed that the reader has thought about the topic before, so that our task is to select rather than to build. The interior of a continuous sample contains many small volumes and small areas, on any of which attention can be focused. A small internal area has the property that, across it, the material on one side exerts a normal force and a tangential force on the material on the other side. Let the normal force be F and the area A; then the ratio F/A approaches a limit as the size of A approaches zero. Thus we define the magnitude of the normal stress at a point across an infinitesimal area of a particular orientation. If we set up Cartesian coordinates so that the orientation of the area can be specified by the direction of its normal then, at a point, for every direction vector there is a normal-stress magnitude. The stress may be compressive or tensile, and in this text we treat compressions as positive. It is possible to imagine a universe where space itself has an attribute of left-handedness or right-handedness, or where space does not but materials do. But if we set these possibilities aside and use ordinary ideas about symmetry, it follows that at any point where stresses exist inside a continuum, there are three orthogonal planes across which the tangential stress is zero; these planes suffer only normal stresses. The planes themselves are principal planes, their normals are the three principal directions at the point and the normal-stress magnitudes are the principal stress magnitudes. The largest, intermediate, and smallest normal compressions will be designated σ 1, σ 2 and σ 3, respectively; for most of what follows we shall designate the directions along which these compressions act as x1, x2, and x3 (so that the plane compressed by stress σ 1 has x1 for its normal), and we shall use x1, x2, and x3 as axes for a local Cartesian system with which other planes and directions at the point can be specified. In particular, for any direction through the point, a unit vector can be imagined (magnitude = 1 unit of length); its components along the three axes will be called n1, n2, and n3, combining to give the unit vector n.

scholarly journals The Electrodonating and Electroaccepting Powers in Atoms

2017 ◽  
Vol 56 (3) ◽  
Author(s):  
Ángel Ulises Orozco-Valencia ◽  
Alberto Vela
Keyword(s):  
Periodic Table ◽  
Alternative Explanation ◽  
Chemical Potential ◽  
Electron Flow ◽  
Neutral Atoms ◽  
Reactivity Indexes ◽  
Definition Of

The derivations that lead to the introduction of the electrophilicity and of the electrodonating and electroaccepting powers are revisited. Special emphasis is given to the role played by the chemical potential of the bath in the definition of these global reactivity indexes. An alternative explanation to the increase of the energy when the system donates electrons is provided. It is also shown that the 2-parabolas model correctly predicts that there is no electron flow when the chemical potential of the bath, μ, is in the interval μ<sup>-</sup> &lt; μ &lt; μ<sup>+</sup>, in almost complete consonance with the ensemble theorem at 0 K. The electrodonating and electroaccepting powers of neutral atoms in the Periodic Table are evaluated and used to explain how the values of these indexes will distribute in the electrodonating-electroaccepting powers plane.

scholarly journals Early Palaeozoic diversifications and extinctions in the marine biosphere: a continuum of change

2019 ◽  
Vol 157 (1) ◽  
pp. 5-21 ◽  
Author(s):  
David A.T. Harper ◽  
Borja Cascales-Miñana ◽  
Thomas Servais
Keyword(s):  
Large Scale ◽  
Analytical Techniques ◽  
Cambrian Explosion ◽  
Ecological Communities ◽  
Time Intervals ◽  
Late Cambrian ◽  
Global Coverage ◽  
Early Palaeozoic ◽  
Marine Biosphere

AbstractA review of biodiversity curves of marine organisms indicates that, despite fluctuations in amplitude (some large), a large-scale, long-term radiation of life took place during the early Palaeozoic Era; it was aggregated by a succession of more discrete and regionalized radiations across geographies and within phylogenies. This major biodiversification within the marine biosphere started during late Precambrian time and was only finally interrupted in the Devonian Period. It includes both the Cambrian Explosion and the Great Ordovician Biodiversification Event. The establishment of modern marine ecosystems took place during a continuous chronology of the successive establishment of organisms and their ecological communities, developed during the ‘Cambrian substrate revolution’, the ‘Ordovician plankton revolution’, the ‘Ordovician substrate revolution’, the ‘Ordovician bioerosion revolution’ and the ‘Devonian nekton revolution’. At smaller scales, different regional but important radiations can be recognized geographically and some of them have been identified and named (e.g. those associated with the ‘Richmondian Invasion’ during Late Ordovician time in Laurentia and the contemporaneous ‘Boda event’ in parts of Europe and North Africa), in particular from areas that were in or moved towards lower latitudes, allowing high levels of speciation on epicontintental seas during these intervals. The datasets remain incomplete for many other geographical areas, but also for particular time intervals (e.g. during the late Cambrian ‘Furongian Gap’). The early Palaeozoic biodiversification therefore appears to be a long-term process, modulated by bursts in significant diversity and intervals of inadequate data, where its progressive character will become increasingly clearer with the availability of more complete datasets, with better global coverage and more advanced analytical techniques.

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