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1.
Pena Julio Nápoles Gonzalo Salgueiro Yamisleydi 《Artificial Intelligence Review》2021,54(5):3817-3847
Artificial Intelligence Review - Attribute weighting is a task of paramount relevance in multi-attribute decision-making (MADM). Over the years, different approaches have been developed to face... 相似文献
2.
Karem Arriaza Constanza Cuevas Eduardo Pena Patricia Siques Julio Brito 《International journal of molecular sciences》2022,23(13)
Hypobaric hypoxia is a condition that occurs at high altitudes (>2500 m) where the partial pressure of gases, particularly oxygen (PO2), decreases. This condition triggers several physiological and molecular responses. One of the principal responses is pulmonary vascular contraction, which seeks to optimize gas exchange under this condition, known as hypoxic pulmonary vasoconstriction (HPV); however, when this physiological response is exacerbated, it contributes to the development of high-altitude pulmonary hypertension (HAPH). Increased levels of zinc (Zn2+) and oxidative stress (known as the “ROS hypothesis”) have been demonstrated in the vasoconstriction process. Therefore, the aim of this review is to determine the relationship between molecular pathways associated with altered Zn2+ levels and oxidative stress in HPV in hypobaric hypoxic conditions. The results indicate an increased level of Zn2+, which is related to increasing mitochondrial ROS (mtROS), alterations in nitric oxide (NO), metallothionein (MT), zinc-regulated, iron-regulated transporter-like protein (ZIP), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-induced protein kinase C epsilon (PKCε) activation in the development of HPV. In conclusion, there is an association between elevated Zn2+ levels and oxidative stress in HPV under different models of hypoxia, which contribute to understanding the molecular mechanism involved in HPV to prevent the development of HAPH. 相似文献
3.
S. Duarte A. Pena C. Delerue-Matos S. Morais M.B.P.P. Oliveira J.A. Pereira 《The Science of the total environment》2010,408(5):1195-1198
Ochratoxin A (OTA) is a mycotoxin produced by a variety of fungi, such as Penicillium verrucosum and Aspergillium spp., which has been found to have a wide number of potentially deadly toxic effects, and can enter the human organism through a variety of means. It then finds its way into the bloodstream and, after a lengthy process, is eventually excreted through the urine. It can thus be detected in its original form not only in blood samples but also in this biological medium. As such, and in an attempt to evaluate the exposure of the Portuguese population to this mycotoxin, morning urine samples were collected during the Winter of 2007, from each of five geographically distinct Portuguese locations — Bragança, Porto, Coimbra, Alentejo, and Algarve — and subjected to extraction by immunoaffinity columns and to OTA quantification through liquid chromatography coupled with fluorescence detection. Prevalent incidence was higher than 95% with Coimbra being the exception (incidence of 73.3%). In nearly all locations, the OTA content of most samples was found to be above the limit of quantification (LOQ) of 0.008 ng/ml. Indeed, excluding Coimbra, with an OTA content level of 0.014 ng/ml, all regions featured content values over 0.021 ng/ml. 相似文献
4.
Inkjet Printing of Self‐Assembled 2D Titanium Carbide and Protein Electrodes for Stimuli‐Responsive Electromagnetic Shielding 下载免费PDF全文
Mert Vural Abdon Pena‐Francesch Joan Bars‐Pomes Huihun Jung Hemanth Gudapati Christine B. Hatter Benjamin D. Allen Babak Anasori Ibrahim T. Ozbolat Yury Gogotsi Melik C. Demirel 《Advanced functional materials》2018,28(32)
2D titanium carbides (MXene) possess significant characteristics including high conductivity and electromagnetic interference shielding efficiency (EMI SE) that are important for applications in printed and flexible electronics. However, MXene‐based ink formulations are yet to be demonstrated for proper inkjet printing of MXene patterns. Here, tandem repeat synthetic proteins based on squid ring teeth (SRT) are employed as templates of molecular self‐assembly to engineer MXene inks that can be printed as stimuli‐responsive electrodes on various substrates including cellulose paper, glass, and flexible polyethylene terephthalate (PET). MXene electrodes printed on PET substrates are able to display electrical conductivity values as high as 1080 ± 175 S cm?1, which significantly exceeds electrical conductivity values of state‐of‐the‐art inkjet‐printed electrodes composed of other 2D materials including graphene (250 S cm?1) and reduced graphene oxide (340 S cm?1). Furthermore, this high electrical conductivity is sustained under excessive bending deformation. These flexible electrodes also exhibit effective EMI SE values reaching 50 dB at films with thicknesses of 1.35 µm, which mainly originate from their high electrical conductivity and layered structure. 相似文献
5.
Sagnac loop in ring resonators for tunable optical filters 总被引:1,自引:0,他引:1
General filter architecture using co- and counterpropagation signals are studied. A specific configuration based on a Sagnac loop within a ring resonator is analyzed. Novel tuning, apart from conventional tuning, is achieved by changing the coupling ratio of a coupler through the adjustment of the equivalent loop length. Full equations describing the filter behavior in passive and active configurations, and simple closed-form formulas to compute the tuning, tolerance, and full-width at half-maximum are reported. The performance of these devices is discussed for their application as selective or channel-dropping ultra-narrow-band filters. The effect of losses and their dispersion properties are also discussed. These devices can be conveniently implemented, using silicon- or InP-integrated optic technology, for they have high free spectral ranges. 相似文献
6.
Enrique Alexandre Antonio Pena Manuel Sobreira 《IEEE transactions on information technology in biomedicine》2006,10(4):809-811
This paper discusses the convenience of using two-dimensional (2-D) coding techniques for the compression of electrocardiogram (ECG) signals. These signals present a very clear periodicity that can be exploited by the use of a 2-D time/frequency transform to decorrelate it as much as possible. A brief theoretical approach is given to justify the use of this technique, and a comparison is made between a 2-D and a one-dimensional (1-D) uniform quantization scenarios. The influence of the error as well as the frame size on the estimation of the fundamental period is studied. 相似文献
7.
Compatibility relations of Al2 03 in the quaternary system Zr02-Al2 03 -Si02 -CaO were studied by firing and quenching followed by microscopy and energy-dispersive X-ray examination. A projection of the boundary surface of the primary crystallization volume of Al2 03 was constructed in terms of the CaO, Si02 , and Zr02 contents of the mixtures recalculated to 100 wt%. Two invariant points, where four solids coexist with a liquid phase, are defined, and the positions of the isotherms were established. 相似文献
8.
John J. Petrovic Maria I. Pena Ivar E. Reimanis Michael S. Sandlin Samuel D. Conzone H. Harriet Kung Darryl P. Butt 《Journal of the American Ceramic Society》1997,80(12):3070-3076
The mechanical behavior of MoSi2 reinforced–Si3 N4 matrix composites was investigated as a function of MoSi2 phase content, MoSi2 phase size, and amount of MgO densification aid for the Si3 N4 phase. Coarse-phase MoSi2 -Si3 N4 composites exhibited higher room-temperature fracture toughness than fine-phase composites, reaching values >8 MP·am1/2 . Composite fracture toughness levels increased at elevated temperature. Fine-phase composites were stronger and more creep resistant than coarse phase composites. Room-temperature strengths >1000 MPa and impression creep rates of ∼10−8 s−1 at 1200°C were observed. Increased MgO levels generally were deleterious to MoSi2 -Si3 N4 mechanical properties. Internal stresses due to MoSi2 and Si3 N4 thermal expansion coefficient mismatch appeared to contribute to fracture toughening in MoSi2 -Si3 N4 composites. 相似文献
9.
John J. Petrovic Maria I. Pena H. Harriett Kung 《Journal of the American Ceramic Society》1997,80(5):1111-1116
Details of the fabrication and microstructures of hot-pressed MoSi2 reinforced–Si3 N4 matrix composites were investigated as a function of MoSi2 phase size and volume fraction, and amount of MgO densification aid. No reactions were observed between MoSi2 and Si3 N4 at the fabrication temperature of 1750°C. Composite microstructures varied from particle–matrix to cermet morphologies with increasing MoSi2 phase content. The MgO densification aid was present only in the Si3 N4 phase. An amorphous glassy phase was observed at the MoSi2 –Si3 N4 phase boundaries, the extent of which decreased with decreased MgO level. No general microcracking was observed in the MoSi2 –Si3 N4 composites, despite the presence of a substantial thermal expansion mismatch between the MoSi2 and Si3 N4 phases. The critical MoSi2 particle diameter for microcracking was calculated to be 3 μm. MoSi2 particles as large as 20 μm resulted in no composite microcracking; this indicated that significant stress relief occurred in these composites, probably because of plastic deformation of the MoSi2 phase. 相似文献
10.
Benedicta Ronchi Wim Clymans Ana Lúcia Pena Barão Floor Vandevenne Eric Struyf Okke Batelaan Alain Dassargues Gerard Govers 《SILICON》2013,5(1):115-133
This paper reviews the processes which determine the concentrations of dissolved silicon (DSi) in soil water and proposes a conceptual mechanistic model for understanding the transport of Si through soils to rivers. The net DSi present in natural waters originates from the dissolution of mineral and amorphous Si sources in the soil, as well as precipitation processes. Important controlling factors are soil composition (mineralogy and saturated porosity) and soil water chemistry (pH, concentrations of organic acids, CO2 and electrolytes). Together with production, polymerization and adsorption equations they constitute a mechanistic framework determining DSi concentrations. We discuss how key controls differ across soil horizons and how this can influence the DSi transport. A typical podzol soil profile in a temperate climate is used as an example, but the proposed model is transferrable to other soil types. Additionally, the impact of external forcing factors such as seasonal climatic variations and land use is evaluated. This blueprint for an integrated model is a first step to mechanistic modelling of Si transport processes in soils. Future implementation with numerical methods should validate the model with field measurements. 相似文献