scholarly journals Vitreous Carbon, Geometry and Topology: A Hollistic Approach

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1694
Author(s):  
Patrice Mélinon
Keyword(s):  
Network Architecture ◽  
Complex Structure ◽  
Ground Level ◽  
Laser Deposition ◽  
Vitreous Carbon ◽  
Amorphous Films ◽  
Geometrical Properties ◽  
And Topology ◽  
Triply Periodic ◽  
The Many

Glass-like carbon (GLC) is a complex structure with astonishing properties: isotropic sp2 structure, low density and chemical robustness. Despite the expanded efforts to understand the structure, it remains little known. We review the different models and a physical route (pulsed laser deposition) based on a well controlled annealing of the native 2D/3D amorphous films. The many models all have compromises: neither all bad nor entirely satisfactory. Properties are understood in a single framework given by topological and geometrical properties. To do this, we present the basic tools of topology and geometry at a ground level for 2D surface, graphene being the best candidate to do this. With this in mind, special attention is paid to the hyperbolic geometry giving birth to triply periodic minimal surfaces. Such surfaces are the basic tools to understand the GLC network architecture. Using two theorems (the classification and the uniformisation), most of the GLC properties can be tackled at least at a heuristic level. All the properties presented can be extended to 2D materials. It is hoped that some researchers may find it useful for their experiments.

scholarly journals The ground-level ozone concentration is inversely correlated with the number of COVID-19 cases in Warsaw, Poland

2021 ◽  
Author(s):  
Oskar Wiśniewski ◽  
Wiesław Kozak ◽  
Maciej Wiśniewski
Keyword(s):  
Wind Speed ◽  
Ozone Concentration ◽  
Inverse Correlation ◽  
Ground Level ◽  
Viral Agent ◽  
The Novel ◽  
Weather Factors ◽  
Ground Level Ozone ◽  
The Many ◽  
The Impact

AbstractCOVID-19, which is a consequence of infection with the novel viral agent SARS-CoV-2, first identified in China (Hubei Province), has been declared a pandemic by the WHO. As of September 10, 2020, over 70,000 cases and over 2000 deaths have been recorded in Poland. Of the many factors contributing to the level of transmission of the virus, the weather appears to be significant. In this work, we analyze the impact of weather factors such as temperature, relative humidity, wind speed, and ground-level ozone concentration on the number of COVID-19 cases in Warsaw, Poland. The obtained results show an inverse correlation between ground-level ozone concentration and the daily number of COVID-19 cases.

Post-Processing of Pulsed Laser-Deposited Pzt Thin Films

1991 ◽  
Vol 243 ◽  
Author(s):  
C. K. Chiang ◽  
W. Wong-Ng ◽  
L. P. Cook ◽  
P. K. Schenck ◽  
H. M. Lee ◽  
...  
Keyword(s):  
Thin Films ◽  
Amorphous Material ◽  
Ferroelectric Properties ◽  
Pulsed Laser ◽  
Linear Shrinkage ◽  
Laser Deposition ◽  
Amorphous Films ◽  
Pzt Thin Films ◽  
Si Substrates ◽  
Pzt Thin Film

AbstractPZT thin films were prepared by pulsed laser deposition on unheated Ptcoated Si substrates. As deposited, the films were amorphous. Films crystallized at 550 - 600 °C to produce predominantly crystalline ferroelectric PZT. Crystallization of the amorphous material was accompanied by a linear shrinkage of ∼2 %, as manifested in development of cracks in the film. Spacing, width and morphology of larger cracks followed a regular progression with decreasing film thickness. For film thicknesses less than 500 runm, much of the shrinkage was taken up by small, closely-spaced cracks of local extent. Implications for measurement of PZT thin film ferroelectric properties and processing are discussed.

scholarly journals Composition Classification of Ultra-High Energy Cosmic Rays

Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 998
Author(s):  
Luis Javier Herrera ◽  
Carlos José Todero Peixoto ◽  
Oresti Baños ◽  
Juan Miguel Carceller ◽  
Francisco Carrillo ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Cosmic Rays ◽  
Computational Cost ◽  
Simulated Data ◽  
Ground Level ◽  
High Energy ◽  
Monte Carlo Code ◽  
High Energy Cosmic Rays ◽  
Research Fields ◽  
The Many

The study of cosmic rays remains as one of the most challenging research fields in Physics. From the many questions still open in this area, knowledge of the type of primary for each event remains as one of the most important issues. All of the cosmic rays observatories have been trying to solve this question for at least six decades, but have not yet succeeded. The main obstacle is the impossibility of directly detecting high energy primary events, being necessary to use Monte Carlo models and simulations to characterize generated particles cascades. This work presents the results attained using a simulated dataset that was provided by the Monte Carlo code CORSIKA, which is a simulator of high energy particles interactions with the atmosphere, resulting in a cascade of secondary particles extending for a few kilometers (in diameter) at ground level. Using this simulated data, a set of machine learning classifiers have been designed and trained, and their computational cost and effectiveness compared, when classifying the type of primary under ideal measuring conditions. Additionally, a feature selection algorithm has allowed for identifying the relevance of the considered features. The results confirm the importance of the electromagnetic-muonic component separation from signal data measured for the problem. The obtained results are quite encouraging and open new work lines for future more restrictive simulations.

Pulsed Laser Deposition of Thin Metallic Multilayers and Amorphous Films

1992 ◽  
Vol 285 ◽  
Author(s):  
Hans-Ulrich Krebs ◽  
Olaf Bremert
Keyword(s):  
Ablation Threshold ◽  
Pulsed Laser ◽  
Film Surface ◽  
The Other ◽  
Laser Deposition ◽  
Metallic Multilayers ◽  
Amorphous Films ◽  
Deposition Rates ◽  
Excimer Laser Ablation ◽  
Explosive Evaporation

ABSTRACTThe method of pulsed excimer laser ablation using KrF radiation was applied for the deposition of thin metallic elementary multilayers. Above an ablation threshold of about 5 J/cm2 an ‘explosive’ evaporation of the metallic targets occurs leading to high deposition rates of up to 5 nm/s. For different metals, the ablation threshold slightly varies leading at the same laser fluence to different growth rates as shown for Ag, Fe, Zr and Nb. By using two elementary targets and adjusting the dwelling times on both targets, Fe/Ag, Fe/Zr and Fe/Nb multilayers of different bilayer thicknesses were deposited. While Fe/Ag superstructures show crystalline phases down to a periodicity of 1 nm, Fe/Zr and Fe/Nb films are amorphous at such wavelengths. On the other side, Fe/Nb multilayers can also be amorphized by a solid state interdiffusion reaction of the elementary multilayers. The surfaces of the grown films are smooth except for a small number of droplets on the film surface.

Characterization of AgAsS and AgSbS amorphous films prepared by pulsed laser deposition

2004 ◽  
Vol 36 (8) ◽  
pp. 1140-1143 ◽  
Author(s):  
T. Wagner ◽  
M. Krbal ◽  
J. Gutwirth ◽  
P. Nemec ◽  
Mir. Vlcek ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Amorphous Films

scholarly journals Surgical Treatment of Wounds Using Stem Cells in Epidermolysis Bullosa (EB)

2021 ◽  
Author(s):  
Magdalena Nita ◽  
Jacek Pliszczyński ◽  
Andrzej Eljaszewicz ◽  
Marcin Moniuszko ◽  
Tomasz Ołdak ◽  
...  
Keyword(s):  
Stem Cells ◽  
Epidermolysis Bullosa ◽  
Skin Diseases ◽  
Complex Structure ◽  
Mechanical Stimuli ◽  
Treatment Methods ◽  
New Treatment ◽  
Induced Pluripotent ◽  
The Many ◽  
Treatment Of Wounds

Epidermolysis bullosa (EB) is a group of hereditary skin diseases, or genodermatoses, characterized by the formation of severe, chronic blisters with painful and life-threatening complications. Despite the previous and ongoing progress in the field, there are still no effective causative treatments for EB. The treatment is limited to relieving symptoms, which—depending on disease severity—may involve skin (blisters, poorly healing wounds caused by the slightest mechanical stimuli, contractures, scarring, pseudosyndactyly) and internal organ abnormalities (esophageal, pyloric, or duodenal atresia; renal failure; and hematopoietic abnormalities). The last decade saw a series of important discoveries that paved the way for new treatment methods, including gene therapy, bone marrow transplantation, cell therapy (allogenic fibroblasts, mesenchymal stem cells [MSCs], and clinical use of induced pluripotent stem cells. Tissue engineering experts are attempting to develop skin-like structures that can facilitate the process of healing to promote skin reconstruction in injuries that are currently incurable. However, this is incredibly challenging, due to the complex structure and the many functions of the skin. Below, we characterize EB and present its potential treatment methods. Despite the cure for EB being still out of reach, recent data from animal models and initial clinical trials in humans have raised patients’, clinicians’, and researchers’ expectations. Consequently, modifying the course of the disease and improving the quality of life have become possible. Moreover, the conclusions drawn based on EB treatment may considerably improve the treatment of other genetic diseases.

scholarly journals The ground level ozone concentration is inversely correlated with the number of COVID-19 cases in Warsaw, Poland

2020 ◽  
Author(s):  
Oskar Wisniewski ◽  
Wieslaw Kozak ◽  
Maciej Wisniewski
Keyword(s):  
Wind Speed ◽  
Ozone Concentration ◽  
Inverse Correlation ◽  
Ground Level ◽  
Viral Agent ◽  
The Novel ◽  
Weather Factors ◽  
Ground Level Ozone ◽  
The Many ◽  
The Impact

COVID-19, which is a consequence of infection with the novel viral agent SARS-CoV-2, first identified in China (Hubei Province), has been declared a pandemic by the WHO. As of September 10, 2020, over 70,000 cases and over 2,000 deaths have been recorded in Poland. Of the many factors contributing to the level of transmission of the virus, the weather appears to be significant. In this work we analyse the impact of weather factors such as temperature, relative humidity, wind speed and ground level ozone concentration on the number of COVID-19 cases in Warsaw, Poland. The obtained results show an inverse correlation between ground level ozone concentration and the daily number of COVID-19 cases.

Quantization and topology: SL(2,R)-de Sitter invariant fields in two dimensions

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040018
Author(s):  
Henri Epstein ◽  
Ugo Moschella
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Two Dimensions ◽  
Quantum Field ◽  
Two Dimensional ◽  
De Sitter ◽  
Cosmological Background ◽  
Local Commutativity ◽  
And Topology ◽  
The Many

We explore the interplay between quantization, local commutativity and the analyticity properties of the two-point functions of a quantum field in a non trivial topological cosmological background in the example of the two-dimensional de Sitter manifold and its double covering. The global topological differences make the many of the well-known features of de Sitter quantum field theory disappear. In particular there is nothing like a Bunch-Davies vacuum and there are no [Formula: see text]-invariant fields whose mass is less than 1/2.

Sign in / Sign up

Export Citation Format

Share Document