scholarly journals 15N NMR Shifts of Eumelanin Building Blocks in Water: A Combined Quantum Mechanics/Statistical Mechanics Approach

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3616
Author(s):  
Leonardo Bruno Assis Oliveira ◽  
Tertius L. Fonseca ◽  
Benedito J. C. Cabral
Keyword(s):  
Quantum Mechanics ◽  
Statistical Mechanics ◽  
Gas Phase ◽  
Marked Effect ◽  
Complex Structure ◽  
Building Blocks ◽  
15N Nmr ◽  
Magnetic Shielding ◽  
Atomic Orbitals ◽  
Theoretical Results

Theoretical results for the magnetic shielding of protonated and unprotonated nitrogens of eumelanin building blocks including monomers, dimers, and tetramers in gas phase and water are presented. The magnetic property in water was determined by carrying out Monte Carlo statistical mechanics sampling combined with quantum mechanics calculations based on the gauge-including atomic orbitals approach. The results show that the environment polarization can have a marked effect on nitrogen magnetic shieldings, especially for the unprotonated nitrogens. Large contrasts of the oligomerization effect on magnetic shielding show a clear distinction between eumelanin building blocks in solution, which could be detected in nuclear magnetic resonance experiments. Calculations for a π-stacked structure defined by the dimer of a tetrameric building block indicate that unprotonated N atoms are significantly deshielded upon π stacking, whereas protonated N atoms are slightly shielded. The results stress the interest of NMR experiments for a better understanding of the eumelanin complex structure.

scholarly journals On Russell’s 1927 Book The Analysis of Matter

Philosophies ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 40
Author(s):  
Said Mikki
Keyword(s):  
General Relativity ◽  
Quantum Mechanics ◽  
Building Blocks ◽  
Bertrand Russell ◽  
Important Work ◽  
Philosophy Of Nature ◽  
Foundations Of Physics ◽  
The World ◽  
Ordinal Space ◽  
Historical Fact

The goal of this article is to bring into wider attention the often neglected important work by Bertrand Russell on the philosophy of nature and the foundations of physics, published in the year 1927. It is suggested that the idea of what could be named Russell space, introduced in Part III of that book, may be viewed as more fundamental than many other types of spaces since the highly abstract nature of the topological ordinal space proposed by Russell there would incorporate into its very fabric the emergent nature of spacetime by deploying event assemblages, but not spacetime or particles, as the fundamental building blocks of the world. We also point out the curious historical fact that the book The Analysis of Matter can be chronologically considered the earliest book-length generic attempt to reflect on the relation between quantum mechanics, just emerging by that time, and general relativity.

Bilberry xyloglucan—novel building blocks containing β-xylose within a complex structure

2007 ◽  
Vol 342 (2) ◽  
pp. 170-181 ◽  
Author(s):  
Hauke Hilz ◽  
Laura E. de Jong ◽  
Mirjam A. Kabel ◽  
René Verhoef ◽  
Henk A. Schols ◽  
...  
Keyword(s):  
Complex Structure ◽  
Building Blocks

Highly regioselective surface acetylation of cellulose and shaped cellulose constructs in the gas-phase

2021 ◽  
Author(s):  
Tetyana Koso ◽  
Marco Beaumont ◽  
Blaise Tardy ◽  
Daniel Rico del Cerro ◽  
Samuel Eyley ◽  
...  
Keyword(s):  
Gas Phase ◽  
Liquid Crystalline ◽  
Computational Modelling ◽  
Building Blocks ◽  
Cellulosic Materials ◽  
Gas Phase Chemistry ◽  
Liquid Crystalline Phases ◽  
Phase Chemistry ◽  
Cholesteric Liquid Crystalline ◽  
Surface Acetylation

Gas-phase acylation of cellulose is an attractive method for modifying the surface properties of cellulosics. However, little is known concerning the regioselectivity of the chemistry, in terms of which cellulose positions are preferentially acylated and if acylation can be restricted to the surface, preserving crystallinities/morphologies. Consequently, we reexplore simple gas-phase acetylation of modern-day cellulosic building blocks – cellulose nanocrystals, pulps, regenerated fibre and aerogels. The gas-phase acetylation is shown to be highly regioselective for the C6-OH, is further supported with computational modelling. This contrasts with liquid-state acetylation, highlighting that the gas-phase chemistry is much more controllable, yet with similar kinetics to the uncatalyzed liquid-phase reactions. Furthermore, this method preserves both the native crystalline structure of cellulose and the supramolecular morphologies of even delicate cellulosic constructs (aerogel exhibiting retention of chiral cholesteric liquid crystalline phases). Therefore, we are convinced that this methodology will lead to more rapid adoption of precisely tailored and cellulosic materials

Thermocouple Response Characteristics in Deflagrating Low-Conductivity Materials

1971 ◽  
Vol 93 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Nam P. Suh ◽  
C. L. Tsai
Keyword(s):  
Theoretical Model ◽  
Gas Phase ◽  
Wire Diameter ◽  
Solid Propellants ◽  
Optimum Ratio ◽  
Response Characteristics ◽  
Bead Diameter ◽  
Double Base ◽  
Theoretical Results ◽  
Good Agreement

The transient thermocouple response characteristics in deflagrating low-conductivity materials with high temperature gradients were investigated theoretically and experimentally. The theoretical model considers the thermocouple bead and lead wires separately, and the two resulting partial differential equations are solved simultaneously by a finite difference technique. The experimental results are obtained by embedding various size thermocouple wires in double-base solid propellants and consequently measuring the temperature profiles and the surface temperatures. The theoretical model is used to predict the experimentally measured temperatures. There is good agreement. The experimentally measured values are smaller than the correct surface temperature, corresponding to the model prediction for zero wire diameter, by at least 20 percent even when 1/2-mil thermocouple wire is used. Both the experimental and theoretical results show a plateau when the thermocouple bead emerges from the solid into the gas phase. The theoretical results also show that there is an optimum ratio of. the thermocouple bead diameter to the wire diameter, which is found to be close to three

The Possibility of Quantum Medicine in Cancer Research: A Review

2021 ◽  
pp. 1-20
Author(s):  
Mahsa Faramarzpour ◽  
Mohammadreza Ghaderinia ◽  
Hamed Abadijoo ◽  
Hossein Aghababa
Keyword(s):  
Quantum Mechanics ◽  
Cancer Biology ◽  
Quantum Physics ◽  
Review Paper ◽  
Building Blocks ◽  
Physical World ◽  
Quantum Mechanical ◽  
Quantum Biology ◽  
Biological Phenomena ◽  
Game Changer

There is no doubt that quantum mechanics has become one of the building blocks of our physical world today. It is one of the most rapidly growing fields of science that can potentially change every aspect of our life. Quantum biology is one of the most essential parts of this era which can be considered as a game-changer in medicine especially in the field of cancer. Despite quantum biology having gained more attention during the last decades, there are still so many unanswered questions concerning cancer biology and so many unpaved roads in this regard. This review paper is an effort to answer the question of how biological phenomena such as cancer can be described through the quantum mechanical framework. In other words, is there a correlation between cancer biology and quantum mechanics, and how? This literature review paper reports on the recently published researches based on the principles of quantum physics with focus on cancer biology and metabolism.

Effect of surface on the gas-phase oxidation of methanol catalysed by nitric oxide

1964 ◽  
Vol 17 (5) ◽  
pp. 539
Author(s):  
JJ Batten
Keyword(s):  
Nitric Oxide ◽  
Gas Phase ◽  
Marked Effect ◽  
Volume Ratio ◽  
Oxidation Of Methanol ◽  
Inorganic Substances ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Kinetics Of ◽  
Effect Of Surface

A study has been made of the effect of the surface-to-volume ratio of the reaction vessel and of coatings of various inorganic substances on the vessel walls on the gas-phase oxidation of methanol catalysed by nitric oxide. The results show that, whereas packing the vessel does not have a marked effect on the rate, the kinetics of the reaction are profoundly influenced by the nature of the surface. The results suggest that the methanol-oxidation chains are initiated at the surface by reaction between methanol and nitrogen dioxide, and that HO2 radicals play an important role in the subsequent chain reaction.

scholarly journals Discrete multiporphyrin pseudorotaxane assemblies from di- and tetravalent porphyrin building blocks

2015 ◽  
Vol 11 ◽  
pp. 748-762 ◽  
Author(s):  
Mirko Lohse ◽  
Larissa K S von Krbek ◽  
Sebastian Radunz ◽  
Suresh Moorthy ◽  
Christoph A Schalley ◽  
...  
Keyword(s):  
Gas Phase ◽  
Self Assembly ◽  
Building Blocks ◽  
Ammonium Ion ◽  
Ion Binding ◽  
Binding Motif ◽  
Functional Nanostructures ◽  
Alternative Structures ◽  
Binding Stoichiometry ◽  
Esi Mass Spectrometry

Two pairs of divalent and tetravalent porphyrin building blocks carrying the complementary supramolecular crown ether/secondary ammonium ion binding motif have been synthesized and their derived pseudorotaxanes have been studied by a combination of NMR spectroscopy in solution and ESI mass spectrometry in the gas phase. By simple mixing of the components the formation of discrete dimeric and trimeric (metallo)porphyrin complexes predominates, in accordance to binding stoichiometry, while the amount of alternative structures can be neglected. Our results illustrate the power of multivalency to program the multicomponent self-assembly of specific entities into discrete functional nanostructures.

scholarly journals A QUANTUM IS A COMPLEX STRUCTURE ON CLASSICAL PHASE SPACE

2005 ◽  
Vol 02 (04) ◽  
pp. 633-655
Author(s):  
JOSÉ M. ISIDRO
Keyword(s):  
Quantum Mechanics ◽  
Phase Space ◽  
Degrees Of Freedom ◽  
Complex Structure ◽  
Classical Mechanics ◽  
Elementary Excitation ◽  
Differentiable Structure ◽  
Duality Transformations ◽  
Kähler Potential ◽  
Classical Phase Space

Duality transformations within the quantum mechanics of a finite number of degrees of freedom can be regarded as the dependence of the notion of a quantum, i.e., an elementary excitation of the vacuum, on the observer on classical phase space. Under an observer we understand, as in general relativity, a local coordinate chart. While classical mechanics can be formulated using a symplectic structure on classical phase space, quantum mechanics requires a complex-differentiable structure on that same space. Complex-differentiable structures on a given real manifold are often not unique. This article is devoted to analysing the dependence of the notion of a quantum on the complex-differentiable structure chosen on classical phase space. For that purpose we consider Kähler phase spaces, endowed with a dynamics whose Hamiltonian equals the local Kähler potential.

Sign in / Sign up

Export Citation Format

Share Document