Learning Neuroimaging Bravo-Rodríguez, Francisco de Asís; Diaz-Aguilera, Rocío; Jr, L. Celso Hygino Cruz
2011, 20120101, 20110923, 2011-11-30, Letnik:
2
eBook
This book is intended as an introduction to neuroradiology and aims to provide the reader with a comprehensive overview of this highly specialized radiological subspecialty. One hundred illustrated ...cases from clinical practice are presented in a standard way. Each case is supported by representative images and is divided into three parts: a brief summary of the patients medical history, a discussion of the disease, and a description of the most characteristic imaging features of the disorder. The focus is not only on common neuroradiological entities such as stroke and acute head trauma but also on less frequent disorders that the practitioner should recognize. Learning Neuroimaging: 100 Essential Casesis an ideal resource for neuroradiology and radiology residents, neurology residents, neurosurgery residents, nurses, radiology technicians, and medical students.
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•Carbon-supported Bi nanoparticles were used to fabricate Bi Gas Diffusion Electrodes (Bi-GDEs).•Formate was obtained in a continuous mode with one pass in a filter-press ...reactor.•Bi-GDEs were able to work at a current density up to 300 mA cm−2.•At 200 mA cm−2, 4 g L−1 of formate was obtained with a high Faradaic Efficiency (80%).•Concentrations of formate of up to 18 g L−1 were obtained.
Electrocatalytic reduction of CO2 has been taken into consideration as a fascinating option to store energy from intermittent renewable sources in the form of chemical value-added products. Among the different value-added products, formic acid or formate is particularly attractive since it can be used as a fuel for low-temperature fuel-cells and as a renewable hydrogen carrier. Very recently, a rapidly increasing number of studies have revealed Bi as a promising electrocatalytic material for the CO2 electroreduction to formate, but the performance of Bi electrodes operating in a continuous mode and high current density (j) has been hardly investigated yet. Thus, this work aims at studying the CO2 electroreduction to formate working in a continuous mode in a filter-press-reactor at a j up to 300 mA·cm−2 using Bi electrodes. Bismuth Gas Diffusion Electrodes (Bi-GDEs) were fabricated from carbon-supported Bismuth-nanoparticles. The influence of j and the electrolyte flow/area ratio in the performance of the Bi-GDEs towards formate were evaluated. Working at j of 300 mA·cm−2, a concentration of 5.2 g formate·L−1 with a faradaic efficiency (FE) and rate of 70% and 11 mmol·m−2·s−1, respectively were achieved. Lowering the j to 90 mA·cm−2, formate concentrations of up to 7.5 g·L−1 could be obtained with an excellent FE of 90%. Interestingly, the highest concentration of formate obtained was 18 g·L−1, but at expenses of an important decrease in FE. Although the results of this study are interesting and promising, further research is required to increase formate concentration for a future implementation at industrial scale.
Durability criteria were used to evaluate concretes containing Opuntia Ficus Indica (OFI, also called nopal) derivatives: exudate nopal mucilage (eNm), cooked nopal mucilage (cNm), and dehydrated ...nopal powder (dNp). Concrete containing eNm and cNm was fabricated using 4%, 8%, 15%, and 30% concentrations by water mass replacement. The dNp was added at 1%, 2%, and 4% (per cement weight) by sand mass replacement. Concrete’s physical and mechanical performance was monitored for the nopal derivative treatments and the control (without nopal derivatives), to quantify any possible durability improvements.
The durability tests included: saturated electrical resistivity (ρS); total voids percentage (TV%), capillary absorption (effective porosity, εEF); compressive strength (fc); rapid chloride permeability (RCP); and SEM micrograph analysis. Because nopal derivatives have an apparently slow reaction time, the tests were evaluated at 30, 90, 180, and 400 days.
Addition of dehydrated nopal powder (dNp) did not improve substantially concrete durability performance, except chloride transport: additions <2% decreased RCP index values up to 10%. Exudate nopal mucilage (eNm) exhibited improved durability index values up to 20% (TV%/εEF decrease and ρS/fc increase), and RCP index was improved up to 30%. Cooked nopal mucilage (cNm), at all four tested ages, produced results superior to the control mixture (between 20% and 40% improvements). In summary, nopal derivatives may act as clogging sponge-like biopolymer within the cement matrix pores, stopping water and chloride transport into concrete.
Natural 2HDMs without FCNCs Diaz-Cruz, J. L.; Saldana-Salazar, U. J.; Tame-Narvaez, K. M. ...
Physical review. D,
08/2021, Letnik:
104, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Motivated by the fermion mass hierarchy, we study the phenomenology of two flavorful two-Higgs-doublet model (2HDM) scenarios. By virtue of the flavor or singular alignment ansatz, it is possible to ...link the mass of a subset of fermions to the vacuum expectation value (VEV) of a unique Higgs doublet and to simultaneously avoid flavor-changing-neutral-currents at tree level. We explicitly construct two models called Type A and B. There, either the top quark alone or all third generation fermions couple to the doublet with the larger VEV. The other fermions acquire their masses through the small VEV of the other doublet. Thus, more natural values for the Yukawa couplings can be obtained. The main differences between these models and conventional ones are studied, including a discussion of both their structure and phenomenological consequences. In particular, as distinctive deviations for the Yukawa couplings of the light fermions are predicted, we discuss possible tests at the LHC based on searches for h → J / Ψ + γ, h → μμ and heavy scalar resonances decaying to muon pairs. We find that for a wide region of parameter space, this specific set of signatures can be used to distinguish among the new proposed types and the conventional ones.
Blends of chitosan (from Cuban lobster) and clay micro/nanoparticles were prepared by dispersion of the clay particles in the film matrix and the films obtained were characterized in terms of water ...solubility, water vapor, oxygen and carbon dioxide permeability, optical, mechanical and thermal properties using an Instron universal testing machine, differential scanning calorimetry, thermogravimetric analyses and scanning electron microscopy (
SEM). The water vapor barrier properties of the films were significantly improved by incorporation of clay in their composition, while the water solubility decreased as the clay concentration increased (for a constant chitosan concentration). The tensile strength of chitosan/clay films increased significantly with increasing chitosan and clay concentrations, while the values of elongation decreased slightly for high values of chitosan concentration.
T
m
increased with the increase of chitosan concentration, but the changes in
T
m
with the addition of clay were not significant.
Polynomial models were fitted to the experimental data in order to facilitate future design of chitosan/clay film systems.
The search for flavons with a mass of O(1) TeV at current and future colliders might probe low-scale flavor models. We are interested in the simplest model that invokes the Froggatt-Nielsen ...mechanism with an Abelian flavor symmetry, which includes a Higgs doublet and a Froggatt-Nielsen complex singlet. Assuming a CP conserving scalar potential, there are a CP-even HF and a CP-odd AF flavons with lepton flavor violating (LFV) couplings. The former can mix with the standard-model-like Higgs boson, thereby inducing tree-level LFV Higgs interactions that may be at the reach of the LHC. We study the constraints on the parameter space of the model from low-energy LFV processes, which are then used to evaluate the flavon decay widths and the gg→ϕ→τμ (ϕ=HF,AF) production cross section at hadron colliders. After imposing several kinematic cuts to reduce the standard model main background, we find that for mHF about 200–350 GeV, the decay HF→τμ might be at the reach of the LHC for a luminosity in the range 1–3 ab−1, however, a luminosity of the order of 10 ab−1 would be required to detect the AF→τμ decay. On the other hand, a future 100 TeV pp collider could probe masses as high as O(10) TeV if it reaches an integrated luminosity of at least 20 ab−1. Therefore, the 100 TeV Collider could work as a flavon factory.
KMgF3 fluoroperovskite doped with thulium at different concentrations were synthesized by the solid-state reaction method. The phase composition and the thermal stability up to 600 °C of the ...polycrystals were analyzed by X-ray diffraction and thermogravimetric analysis, respectively. The KMgF3 at 1.0 mol% of Tm polycrystals showed the best thermal stability and did not present another phase. The gamma radiation (0.1–10 kGy) effect in thulium-doped KMgF3 produced the F color centers, and their aggregates such as F2, and F3 centers. The F centers, and the potassium vacancies (VK−) in the fluoroperosvkites were analyzed by the optical absorption and emission measurements. Optical absorption at 275 nm and 443 nm were assigned to F and F2, respectively, in undoped KMgF3. Tm-doped fluoroperovskite shows the optical absorption bands at 277, 393, 432, and 577 nm, which were ascribed to the F, F3, F2 and VK− centers, respectively. When the F band for undoped polycrystals was excited at 275 nm, a clear emission associated with F2 and F3 centers was observed. In the case of Tm-doped, an enhancement of the blue emission at 457 nm occurred and a UV band (354 nm) was observed upon exciting the F band. The blue emission of thulium was overlapped with the F3 color center band. The emission bands at 457 and 354 nm were ascribed to 1D2 - 3F4 and 1D2 - 3H6 transitions of Tm in KMgF3. The optical absorption and glow curves were investigated too. The glow curves were assisted by the color centers, vacancies, and thulium impurity. Thermal bleaching shows that the F center was the main participant to give rise to the TL intensity of the glow curves. Thulium acts as a deep electron trap in the bandgap of the KMgF3 fluoroperovskites forming TL peak at the higher temperature, from 430 to 408 °C. The absorption, emission, and thermoluminescence glow peaks of the undoped and Tm-doped KMgF3 were compared.
•Thulium-doped KMgF3 polycrystals were synthesized by solid-state reaction method.•Optical absorption at 275 and 443 nm were assigned to F and F2, respectively, in KMgF3.•KMgF3:Tm shows OA at 277, 393, 432, and 577 nm, ascribed to F, F3, F2 and VK− centers.•Emission at 457 and 354 nm were assigned to 1D2 - 3F4 and 1D2 - 3H6 transitions of Tm in KMgF3.•Thermal bleaching shows F center has the main influence on the TL glow curves.
The paper focuses on the evaluation of the effective properties of linear viscoelastic composites with a periodic structure, containing long cylindrical fibers of circular cross-section and for two ...different cell arrangements: square and hexagonal unit cells. For this purpose, we use the two-scale asymptotic homogenization method (AHM) and a numerical homogenization method (NHM). Based on the correspondence principle, the local functions and the relaxation overall properties are obtained in explicit form by the AHM using the Prony series. Additionally, the NHM is established for a three-dimensional representative cell, and the problem is solved under appropriate boundary conditions, by using the Finite Element Method. The numerical results obtained by the AHM and NHM are compared and verified with other theoretical approaches. The comparisons show a good agreement and a benchmark for further experimental and theoretical investigations.
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