273 research outputs found
Estudio de un magnetrón utilizando el método de elementos finitos
Magnetron sputtering system is a technique that consists in extracting atoms from a target
material by collisions of energetic ions of an inert gas. It is widely used in semiconductor industries
and materials processing research for developing thin films by deposition. During this
process a low temperature capacitively coupled plasma is generated near the cathode and several
variations of the properties of this plasma can affect the thin film deposition process and
quality. An approach to study these types of systems is by computational modeling. The use
of robust computational codes that can handle complicated geometries and can solve complex
systems of differential equations. In this present project we aim to model numerically a system
of magnetrons developed at the Materials Science and Renewable Energies (MatER) laboratory.
Using the geometry measurements and the material properties of each component taken in
the laboratory, a CAD geometry was developed. Furthermore, the electric and magnetic fields
are solved for the geometry configuration and, by implementing a Monte Carlo simulation, the
electron trajectories and velocity distributions in the system are calculated. Finally, we use a
multi-fluid model to solve a simplified system of a 1 dimensional capacitively coupled plasma
and recover the system properties. The method to solve the respective system of equations is
the finite element method implemented in the software COMSOL Multiphysics.Trabajo de investigaciĂł
First-principles study of point defects at semicoherent interface
Modeling semicoherent metal-metal interfaces has so far been performed using
atomistic simulations based on semiempirical interatomic potentials. We
demonstrate through more precise ab-initio calculations that key conclusions
drawn from previous studies do not conform with the new results which show that
single point defects do not delocalize near the interfacial plane, but remain
compact. We give a simple qualitative explanation for the difference in
predicted results that can be traced back to shortcomings in potential fitting
A scalable parallel Monte Carlo algorithm for atomistic simulations of precipitation in alloys
We present an extension of the semi-grandcanonical (SGC) ensemble that we
refer to as the variance-constrained semi-grandcanonical (VC-SGC) ensemble. It
allows for transmutation Monte Carlo simulations of multicomponent systems in
multiphase regions of the phase diagram and lends itself to scalable
simulations on massively parallel platforms. By combining transmutation moves
with molecular dynamics steps structural relaxations and thermal vibrations in
realistic alloys can be taken into account. In this way, we construct a robust
and efficient simulation technique that is ideally suited for large-scale
simulations of precipitation in multicomponent systems in the presence of
structural disorder. To illustrate the algorithm introduced in this work, we
study the precipitation of Cu in nanocrystalline Fe.Comment: 12 pages; 10 figure
New simulations to qualify eutectic lithium-lead as breeder material
Pb17Li is today a reference breeder material in diverse fusion R&D programs worldwide. One of the main issues is the problem of liquid metals breeder blanket behavior. The knowledge of eutectic properties like optimal composition, physical and thermodynamic behavior or diffusion coefficients of Tritium are extremely necessary for current designs. In particular, the knowledge of the function linking the tritium concentration dissolved in liquid materials with the tritium partial pressure at a liquid/gas interface in equilibrium, CT =f(PT ), is of basic importance because it directly impacts all functional properties of a blanket determining: tritium inventory, tritium permeation rate and tritium extraction efficiency. Nowadays, understanding the structure and behavior of this compound is a real goal in fusion engineering and materials science. Atomistic simulations of liquids can provide much information; not only supplementing experimental data, but providing new tests of theories and ideas, making specific predictions that require experimental tests, and ultimately helping to a deeper understandin
Chemotherapy-induced alopecia management: Clinical experience and practical advice
Background:
Chemotherapy-induced alopecia (CIA) is probably one of the most
shocking aspects for oncological patients and underestimated by physicians. Among
hair loss risk factors, there are treatment-related aspects such as drug dose, admin-
istration regimen, and exposure to X-rays, but also patient-related characteristics. To
the best of our knowledge, no guidelines are available about CIA management.
Aims and methods:
With this study, based on literature background and our clinical
experience, we would like to propose a list of actions in order to estimate the risk
of hair loss before starting chemotherapy and to manage this condition before, dur-
ing, and after drug administration and to create a sort of practical guide for derma-
tologists and oncologists.
Results and conclusion:
There is an urgent need for prospective studies to clarify
the mechanistic basis of alopecia associated with these drugs and consequently to
design evidence-based management strategies
Multi-therapies in androgenetic alopecia: review and clinical experiences.
Androgenetic alopecia (AGA) is a genetically determined progressive hair-loss condition
which represents the most common cause of hair loss in men. The use of the medical term
androgenetic alopecia reflects current knowledge about the important role of androgens and genetic
factors in its etiology. In addition to androgen-dependent changes in the hair cycle, sustained
microscopic follicular inflammation contributes to its onset. Furthermore, Prostaglandins have been
demonstrated to have the ability in modulating hair follicle cycle; in particular, PGD2 inhibits hair
growth while PGE2/F2a promote growth. Due to the progressive nature of AGA, the treatment should
be started early and continued indefinitely, since the benefit will not be maintained upon ceasing
therapy. To date, only two therapeutic agents have been approved by the Food and Drug
Administration and European Medicines Agency for the treatment of AGA: topical minoxidil and oral
finasteride. Considering the many pathogenetic mechanisms involved in AGA, various treatment
options are available: topical and systemic drugs may be used and the choice depends on various
factors including grading of AGA, patientsâ pathological conditions, practicability, costs and risks. So,
the treatment for AGA should be based on personalized therapy and targeted at the different
pathophysiological aspects of AG
Are there stable long-range ordered Fe(1-x)Cr(x) compounds?
The heat of formation of Fe-Cr alloys undergoes an anomalous change of sign
at small Cr concentrations. This observation raises the question whether there
are intermetallic phases present in this composition range. Here we report the
discovery of several long-range ordered structures that represent ground state
phases at zero Kelvin. In particular we have identified a structure at 3.7% Cr
with an embedding energy which is 49 meV/Cr atom below the solid solution. This
implies there is an effective long-range attractive interaction between Cr
atoms. We propose that the structures found in this study complete the low
temperature-low Cr region of the phase diagram.Comment: 3 pages, 2 figure
a markov chain based model for wind power prediction in congested electrical grids
The large penetration of wind generators in existing electrical grids induces critical issues that are pushing the system operators to improve several critical operation functions, such as the security analysis and the spinning reserve assessment, with the purpose of mitigating the effects induced by the injected power profiles, which are ruled by the intermittent and not-programmable wind dynamics. Although numerous forecasting tools have been proposed in the literature to predict the generated power profiles in function of the estimated wind speed, further and more complex phenomena need to be investigated in order to take into account the effects of the forecasting uncertainty on power system operation. In order to deal with this issue, this paper proposes a probabilistic model based on Markov chains, which predicts the wind power profiles injected into the grid, considering the real generator model and the effects of the power curtailments imposed by the grid operator. Experimental results obtained on a real case study are presented and discussed in order to prove the effectiveness of the proposed method
Androgenetic alopecia: a review
Purpose
Androgenetic alopecia, commonly known as male
pattern baldness, is the most common type of progressive
hair loss disorder in men. The aim of this paper is to review
recent advances in understanding the pathophysiology and
molecular mechanism of androgenetic alopecia.
Methods
Using the PubMed database, we conducted a
systematic review of the literature, selecting studies pub-
lished from 1916 to 2016.
Results
The occurrence and development of androgenetic
alopecia depends on the interaction of endocrine factors and
genetic predisposition. Androgenetic alopecia is character-
ized by progressive hair follicular miniaturization, caused
by the actions of androgens on the epithelial cells of
genetically susceptible hair follicles in androgen-dependent
areas. Although the exact pathogenesis of androgenetic
alopecia remains to be clari
fi
ed, research has shown that it is
a polygenetic condition. Numerous studies have unequi-
vocally identi
fi
ed two major genetic risk loci for androge-
netic alopecia, on the X-chromosome AR
â
EDA2R locus and
the chromosome 20p11 locus.
Conclusions
Candidate gene and genome-wide association
studies have reported that single-nucleotide polymorphisms
at different genomic loci are associated with androgenetic
alopecia development. A number of genes determine the
predisposition for androgenetic alopecia in a polygenic fashion. However, further studies are needed before the
specific genetic factors of this polygenic condition can be
fully explaine
Data-driven Models to Anticipate Critical Voltage Events in Power Systems
This paper explores the effectiveness of data-driven models to predict
voltage excursion events in power systems using simple categorical labels. By
treating the prediction as a categorical classification task, the workflow is
characterized by a low computational and data burden. A proof-of-concept case
study on a real portion of the Italian 150 kV sub-transmission network, which
hosts a significant amount of wind power generation, demonstrates the general
validity of the proposal and offers insight into the strengths and weaknesses
of several widely utilized prediction models for this application.Comment: In proceedings of the 11th Bulk Power Systems Dynamics and Control
Symposium (IREP 2022), July 25-30, 2022, Banff, Canad
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