The thickness of BaTiO3 tape castings as function of the slip system

Román Nava,Sophie Guillemet-Fritsch,Juan Aguilar-Garib,Edgar Reyes,Bernard Durand 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.2

One of the most popular techniques in the fabrication of multilayer ceramic capacitor (MLCC) is tape casting, which requires the preparation of a slip that could be either solvent or water-based. A requirement of MLCC miniaturization has pushed improvement of this technique up to the point of fabricating ceramic films below 10μm. However, less information on a direct comparison of aqueous and non-aqueous slips systems using BaTiO3 for dielectric tapes below 3.5 μm is available in the literature. Therefore, solvent and water-based systems were studied in this research aimed to weight the different factors on the thickness reduction; in particular the relation between slip viscosity and ceramic tape thickness was established for both slips formulations. It was found that viscosity below 100 mPa·s is a not a general rule since there is an important influence of the solvent medium; nevertheless adhesion tape-substrate plays an important role over the thinning of water-based formulations. The slip viscosity is defined by the dispersant type of aqueous systems and the binder of non aqueous systems, while reduction of the powder size is more sensitive to the solvent medium as for polar/non –polar mixtures. Ceramic tape homogeneity is strongly affected by the presence of hard aggregation and should be accounted for with the use of nanoparticles. A condition was also demonstrated where low viscosities and thinner layers are related.

Benign osteoblastoma of the mandible: a case report

María del Carmen Navas-Aparicio(María del Carmen Navas-Aparicio ) 대한구강악안면외과학회 2023 대한구강악안면외과학회지 Vol.49 No.1

Osteoblastoma is a rare benign neoplasm formed by osteoid tissue and well-vascularized bone that occurs mainly in children and adolescents. It appears primarily in the long bones, vertebral column, and small bones of the hands and feet, and not typically in the skull and maxillary bones. The purpose of this study is to present the case of an 8-year-old girl with a diagnosis of right mandibular osteoblastoma and a review of the relevant literature. The goals of treatment were to preserve dental occlusion, masticatory function and facial symmetry while minimizing the effects on patient body image and quality of life. Osteoblastoma, although it is benign, can be aggressive, and its treatment will depend on the timing of diagnosis, size and location. Early diagnosis is essential to avoid not only radical surgery as in the case presented, but also to help minimize the risk of possible relapse and potential malignancy of a benign osteoblastoma.

On the fatigue behavior of support structures for offshore wind turbines

N. Alati,G. Failla,V. Nava,F. Arena,A. Santini 한국풍공학회 2014 한국풍공학회지 Vol.18 No.2

It is believed that offshore wind farms may satisfy an increasing portion of the energy demand in the next years. This paper presents a comparative study of the fatigue performances of tripod and jacket steel support structures for offshore wind turbines in waters of intermediate depth (20-50 m). A reference site at a water depth of 45 m in the North Atlantic Ocean is considered. The tripod and jacket support structures are conceived according to typical current design. The fatigue behavior is assessed in the time domain under combined stochastic wind and wave loading and the results are compared in terms of a lifetime damage equivalent load.

On the fatigue behavior of support structures for offshore wind turbines

Alati, N.,Nava, V.,Failla, G.,Arena, F.,Santini, A. Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.18 No.2

It is believed that offshore wind farms may satisfy an increasing portion of the energy demand in the next years. This paper presents a comparative study of the fatigue performances of tripod and jacket steel support structures for offshore wind turbines in waters of intermediate depth (20-50 m). A reference site at a water depth of 45 m in the North Atlantic Ocean is considered. The tripod and jacket support structures are conceived according to typical current design. The fatigue behavior is assessed in the time domain under combined stochastic wind and wave loading and the results are compared in terms of a lifetime damage equivalent load.

Fluid-structure interaction of a tensile fabric structure subjected to different wind speeds

Jesús G. Valdés-Vázquez,Adrián D. García-Soto,Alejandro Hernández-Martínez,José L. Nava 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.31 No.6

Despite the current technologic developments, failures in existent tensile fabric structures (TFS) subjected to wind do happen. However, design pressure coefficients are only obtained for large projects. Moreover, studies on TFSs with realistic supporting frames, comparing static and dynamic analyses and discussing the design implications, are lacking. In this study, fluid-Structure analyses of a TFS supported by masts and inclined cables, by subjecting it to different wind speeds, are carried out, to gain more understanding in the above-referred aspects. Wind-induced stresses in the fabric and axial forces in masts and cables are assessed for a hypar by using computational fluid dynamics. Comparisons are carried out versus an equivalent static analysis and also versus loadings deemed representative for design. The procedure includes the so-called form-finding, a finite element formulation for the TFS and the fluid formulation. The selected structure is deemed realistic, since the supporting frame is included and the shape and geometry of the TFS are not uncommon. It is found that by carrying out an equivalent static analysis with the determined pressure coefficients, differences of up to 24% for stresses in the fabric, 5.4% for the compressive force in the masts and 21% for the tensile force in the cables are found with respect to results of the dynamic analysis. If wind loads commonly considered for design are used, significant differences are also found, specially for the reactions at the supporting frame. The results in this study can be used as an aid by designers and researchers.

Nanocrystallization process and ferromagnetic properties of amorphous (Fe0.99Mo0.01)78Si9B13 ribbons

Xiang-Cheng Sun,J. Reyes-Gasga,N. Nava,W. S. Sun 한국물리학회 2002 Current Applied Physics Vol.2 No.3

The nanocrystallization process of soft ferromagnetic (Fe0:99Mo0:01)78Si9B13 ribbons has been studied in detail. Microstructural and ferromagnetic properties are examined by transmission electron microscopy (TEM), X-ray diffraction (XRD), Mossbauer spectroscopy (MS), differential scanning calorimetry (DSC) and magnetization measurements. The Curie and crystallization temperatures are determined to be TC ¼ 665 K and Tx ¼ 750 K, respectively. The Tx value is in well agreement with DSC measurement results. XRD patterns had shown two metastable phases (Fe23B6, Fe3 B) which were formed under in situ nanocrystallization process. These metastable phases embedded in the amorphous matrix have a significant effect on magnetic ordering. The ultimate nanocrystalline (NC) phases of a-Fe(Mo, Si) and Fe2B at optimum annealing temperature had been observed respectively. It is notable that the magnetization of the amorphous phase decreases more rapidly with increasing temperature than those of NC ferromagnetism, which suggest the presence of the distribution of exchange interaction in the amorphous phase or high metalloid contents.

Blood-brain Barrier Damage is Pivotal for SARS-CoV-2 Infection to the Central Nervous System

Rodríguez-Morales Jahir,Guartazaca-Guerrero Sebastián,Rizo-Téllez Salma A.,Viurcos-Sanabria Rebeca,Barrón Eira Valeria,Hernández-Valencia Aldo F.,Nava Porfirio,Escobedo Galileo,Carrillo-Ruiz José Dami 한국뇌신경과학회 2022 Experimental Neurobiology Vol.31 No.4

Transsynaptic transport is the most accepted proposal to explain the SARS-CoV-2 infection of the CNS. Nevertheless, emerging evidence shows that neurons do not express the SARS-CoV-2 receptor ACE2, which highlights the importance of the blood-brain barrier (BBB) in preventing virus entry to the brain. In this study, we examine the presence of SARS-CoV-2 messenger ribonucleic acid (mRNA) and the cytokine profile in cerebrospinal fluids (CSF) from two patients with a brain tumor and COVID-19. To determine the BBB damage, we evaluate the Q- albumin index, which is an indirect parameter to assess the permeability of this structure. The Q-albumin index of the patient with an intraventricular brain tumor suggests that the BBB is undamaged, preventing the passage of SARS-CoV-2 and pro-inflammatory molecules. The development of brain tumors that disrupt the BBB (measured by the Q-albumin index), in this case, a petroclival meningioma (Case 1), allows the free passage of the SARS-CoV-2 virus and probably lets the free transit of pro-inflammatory molecules to the CNS, which leads to a possible activation of the microglia (astrogliosis) and an exacerbated immune response represented by IL-13, IFN-γ, and IL-2 trying to inhibit both the infection and the carcinogenic process.

Comparative Experimental and Analytical Modeling of Impact Energy Dissipation of Ultra-High Performance Fibre Reinforced Concrete

Murali G,Venkatesh J.,Lokesh N.,Nava Teja Reddy,Karthikeyan K. 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.8

This study examines the impact energy dissipation capacity of Ultra High Performance Fibre Reinforced Concrete (UHPFRC). Forthis purpose, nine different mixes were fabricated with hooked end and crimped steel fibres at a dosage of 0.5, 1.0, 1.5 and 2.0percentage and tested under pendulum impact test. The impact energy dissipation capacity is assessed based on test (Charpy U-notch)procedure suggested by ASTM E23. Also, an analytical model was adopted to predict the impact energy dissipation value ofUHPFRC and its performance is verified against experimental results. Based on the test results, the impact energy dissipationcapacity of the mixtures containing crimped and hooked end steel fibres were significantly higher than that of Plain Concrete (PC). The hooked end steel fibres had an increased impact energy dissipation capacity compared to crimped steel fibres, which implies thathooked end steel fibre is more appropriate for enhancing the impact energy dissipation of UHPFRC. Also, the modelling datacompared well with experimental data for the fibre volume fraction beyond 0.5%.

Remote Healthcare Program in Mexico in the Context of the COVID-19 Pandemic

Rodolfo Lehmann Mendoza,Gabriela Yanet Cortés Moreno,Hilario Ascensión Martinez Arredondo,Anaya Aguilar Cynthia Jeanet,Pedro Armando Chaidez Rosales,Ilicia González Mundo,Armando Mejía Nava,Adrian H. 대한의료정보학회 2022 Healthcare Informatics Research Vol.28 No.2

Objectives: Given the challenge of limiting the transmission of coronavirus disease 2019 while simultaneously continuingto provide medical care for other chronic and degenerative diseases and monitor therapy, a remote medical advice and guidanceprogram was created to help individuals receive health services at their homes. Methods: A descriptive, cross-sectional,and observational study was performed from April 13, 2020 to April 19, 2021 among Petroleos Mexicanos (PEMEX) healthservices beneficiaries. Mobile text messages were used to assign patients throughout Mexico to a doctor, who coordinateda video call with the nursing service for advice and remote care. Results: In total, 17,472 calls were registered, with an averageduration of 10.28 minutes. Almost half (49.4%) of the people who requested attention through the remote program wereworkers, 31.5% were workers’ relatives, and 19.1% were retired workers. The average age of the program users was 50.66 ±18.02 years. A total of 144 doctors from 28 different specialties participated. In this program, 7,163 calls were made becauseof respiratory symptoms, 1,514 for therapeutic monitoring (prescriptions), and 8,183 because of other diseases, includingmental health. Conclusions: Remote healthcare programs have shown the potential to support the health system. This programis the first to deploy real-time video calls with a health team utilizing institutional electronic clinical records in Mexico. The implementation of this pandemic management program impacted the number of consultations given remotely, resultingin effective triage.

Optical and microphysical properties of fresh biomass burning aerosol retrieved by Raman lidar, and star-and sun-photometry : REMOTE SENSING OF FRESH BB AEROSOL

Alados-Arboledas, L.,Mü,ller, D.,Guerrero-Rascado, J. L.,Navas-Guzmá,n, F.,Pé,rez-Ramí,rez, D.,Olmo, F. J. American Geophysical Union 2011 Geophysical research letters Vol.38 No.1