scholarly journals Fabrication of Porous Al2O3 Ceramics with Submicron-Sized Pores Using a Water-Based Gelcasting Method

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1784 ◽  
Author(s):  
Zhihong Yang ◽  
Nan Chen ◽  
Xiaomei Qin
Keyword(s):  
Mechanical Strength ◽  
Water Content ◽  
Sintering Temperature ◽  
Al2o3 Content ◽  
Volume Fractions ◽  
Pore Sizes ◽  
Water Based ◽  
Low Levels ◽  
Median Pore

The gelcasting method is usually employed to fabricate relatively dense ceramics. In this work, however, porous Al2O3 ceramics with submicron-sized pores were fabricated using the water-based gelcasting method by keeping the Al2O3 content at low levels. By controlling the water content in the ceramic slurries and the sintering temperature of the green samples, the volume fractions and the size characteristics of the pores in the porous Al2O3 can be readily obtained. For the porous Al2O3 ceramics prepared with 30 vol.% Al2O3 content in the slurries, their open porosities were from 38.3% to 47.2%, while their median pore sizes varied from 299.8 nm to 371.9 nm. When there was more Al2O3 content in the slurries (40 vol.% Al2O3), the porous Al2O3 ceramics had open porosities from 37.0% to 46.5%, and median pore sizes from 355.4 nm to 363.1 nm. It was found that a higher sintering temperature and Al2O3 content in the slurries increased the mechanical strength of the porous Al2O3 ceramics.

scholarly journals Hydrometeor and latent heat profiles of tropical cyclones Conson, Ivan and Catarina using PR/TRMM data

2010 ◽  
Vol 25 (2) ◽  
pp. 156-174 ◽  
Author(s):  
Marcelo Barbio Rosa ◽  
Augusto Pereira Filho ◽  
Prakki Satyamurty
Keyword(s):  
Water Content ◽  
Latent Heat ◽  
High Water ◽  
Mean Value ◽  
The Other ◽  
High Water Content ◽  
Hurricane Ivan ◽  
Two Systems ◽  
Low Levels ◽  
Ice Content

ABSTRACT Microphysical and thermodynamical features of two tropical systems, namely Hurricane Ivan and Typhoon Conson, and one sub-tropical, Catarina, have been analyzed based on space-born radar PR measurements available on the TRMM satellite. The procedure to classify the reflectivity profiles followed the Heymsfield et al (2000) and Steiner et al (1995) methodologies. The water and ice content have been calculated using a relationship obtained with data of the surface SPOL radar and PR in Rondonia State in Brazil. The diabatic heating rate due to latent heat release has been estimated using the methodology developed by Tao et al (1990). A more detailed analysis has been performed for Hurricane Catarina, the first of its kind in South Atlantic. High water content mean value has been found in Conson and Ivan at low levels and close to their centers. Results indicate that hurricane Catarina was shallower than the other two systems, with less water and the water was concentrated closer to its center. The mean ice content in Catarina was about 0.05 g kg-1 while in Conson it was 0.06 g kg-1 and in Ivan 0.08 g kg-1. Conson and Ivan had water content up to 0.3 g kg-1 above the 0ºC layer, while Catarina had less than 0.15 g kg-1. The latent heat released by Catarina showed to be very similar to the other two systems, except in the regions closer to the center.

Research on the hard brittle clay shale water content and the mechanical strength distribution rule

2016 ◽  
pp. 607-610
Author(s):  
Guo-Ren Lu ◽  
Ming Liu ◽  
Le-Wen Zhang ◽  
Hao Zhou
Keyword(s):  
Mechanical Strength ◽  
Water Content ◽  
Strength Distribution ◽  
Clay Shale ◽  
Distribution Rule

Structure–property relation of porous poly (l-lactic acid) scaffolds fabricated using organic solvent mixtures and controlled cooling rates and its bio-compatibility with human adipose stem cells

2018 ◽  
Vol 33 (4) ◽  
pp. 397-415 ◽  
Author(s):  
Harish Chinnasami ◽  
Jeff Gimble ◽  
Ram V Devireddy
Keyword(s):  
Stem Cells ◽  
Cell Proliferation ◽  
Lactic Acid ◽  
Phase Separation ◽  
Mechanical Strength ◽  
Separation Method ◽  
Thermally Induced Phase Separation ◽  
Cooling Rates ◽  
Thermally Induced ◽  
Pore Sizes

Thermally induced phase separation method was used to make porous three-dimensional poly (l-lactic acid) scaffolds. The effect of imposed thermal profile during freezing of the poly (l-lactic acid) in dioxane solution on the scaffold was characterized by their micro-structure, porosity (%), pore sizes’ distribution, and mechanical strength. The porosity (%) decreased considerably with increasing concentrations of poly (l-lactic acid) in the solution, while a decreasing trend was observed with increasing cooling rates. The mechanical strength increases with increase in poly (l-lactic acid) concentration and also with increase in the cooling rate for both types of solvents. Therefore, mechanical strength was increased by higher cooling rates while the porosity (%) remained relatively consistent. Scaffolds made using higher concentrations of poly (l-lactic acid; 7% and 10% w/v) in solvent showed better mechanical strength which improved relatively with increasing cooling rates (1°C–40°C/min). This phenomenon of enhanced structural integrity with increasing cooling rates was more prominent in scaffolds made from higher initial poly (l-lactic acid) concentrations. Human adipose–derived stem cells were cultured on these scaffold (7% and 10% w/v) prepared by thermally induced phase separation at all cooling rates to measure the cell proliferation efficiency as a function of their micro-structural properties. Mean pore sizes played a crucial role in cell proliferation than percent porosity since all scaffolds were >88% porous. The viability percent of human adipose tissue–derived adult stem cells increased consistently with longer periods of culture. Thus, poly (l-lactic acid) scaffolds prepared by thermally controlled thermally induced phase separation method could be a prime candidate for making ex vivo tissue-engineered grafts for surgical implantation.

Mechanical strength characterization and modeling of hydroxyapatite/tricalcium phosphate biocomposite using the diametral-compression test

2021 ◽  
Vol 93 (3) ◽  
pp. 30403
Author(s):  
Mohammed Es-Saddik ◽  
Said Laasri ◽  
Abdelaziz Laghzizil ◽  
Jean-Michel Nunzi ◽  
Mohammed Taha ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Tricalcium Phosphate ◽  
Sintering Temperature ◽  
Rupture Strength ◽  
Mechanical Resistance ◽  
The Finite Element Method ◽  
Maximum Value ◽  
Strength Characterization ◽  
Powder Manufacturing ◽  
Diametral Compression Test

This study reports the enhanced mechanical resistance of the composite bioceramics of hydroxyapatite (HAP) and tricalcium phosphate (β-TCP) used as bone substitute. HAP/β-TCP mixture was prepared by wet mixing of powders and characterized. Effects of powder manufacturing and sintering temperature on the densification, microstructure and mechanical properties of the composite were studied. The rupture strength (σr) was calculated using the Brazilian test. At 1250 °C, the relative density and mechanical strength of the HAP/β-TCP ceramics reached the maximum value of 89% and 43 MPa, respectively. Experimental results were modeled by the finite element method to determine the stress distribution in the compacted disc.

The impact of root exclusion on duff moisture and fire danger

2015 ◽  
Vol 45 (8) ◽  
pp. 978-986 ◽  
Author(s):  
Dan K. Thompson ◽  
John Studens ◽  
Chelene Krezek-Hanes ◽  
B. Mike Wotton
Keyword(s):  
Water Content ◽  
Mineral Soil ◽  
Root Water Uptake ◽  
Volumetric Water Content ◽  
Exclusion Experiment ◽  
Stand Type ◽  
Low Levels ◽  
The Impact ◽  
Soil Interface ◽  
Root Exclusion

The impact of root water uptake on duff (both fibric and humic horizons) moisture was investigated at deciduous, mixedwood, and conifer stands in Ontario, Canada. Roots were actively excluded from the duff layer using geotextiles inserted at the duff–mineral soil interface and along the plot edges; liquid and vapour water flow was otherwise not affected by the geotextiles. Root exclusion caused little difference in duff moisture content prior to early June, after which the root exclusion plots remained at 15%–20% volumetric water content, whereas root-intact plots declined to as low as 5% volumetric water content during rain-free periods. Only in the root-intact plots did the duff water content reach sufficiently low levels that duff evaporation was limited by low water content. The net effect of root exclusion was to reduce the cumulative growing season water loss in the duff by 19%–31%, depending on the stand type. Root exclusion also decreased the number of days with a high probability of duff smouldering from as many as 72 days·year−1 to as few as 0 days·year−1. This root exclusion experiment provides a model for short-term duff moisture transitions under thinned forests such as those forests under community wildfire protection.

Colorimetric and ratiometric fluorescence sensing of water based on 9-methyl pyrido[3,4-b]indole-boron trifluoride complex

2019 ◽  
Vol 48 (6) ◽  
pp. 2086-2092 ◽  
Author(s):  
Toshiaki Enoki ◽  
Yousuke Ooyama
Keyword(s):  
Water Content ◽  
Boron Trifluoride ◽  
Fluorescent Sensor ◽  
High Water ◽  
High Water Content ◽  
Ratiometric Fluorescence ◽  
Fluorescence Sensing ◽  
Water Based ◽  
Ratiometric Fluorescence Sensing ◽  
Boron Trifluoride Complex

9-Methyl pyrido[3,4-b]indole-boron trifluoride complex 9-MP-BF3 was developed as a colorimetric and ratiometric fluorescent sensor for the detection of water from the low- to high-water-content regions in solvents.

A-14 THE EFFECT OF SINTERING TEMPERATURE ON MECHANICAL STRENGTH OF ZIRCONIA SINTERED COMPONENT(Session: Ceramics III)

2006 ◽  
Vol 2006 (0) ◽  
pp. 14 ◽  
Author(s):  
Aidah Jumahat ◽  
M. Hussain Ismail ◽  
M. Affendi Shaari
Keyword(s):  
Mechanical Strength ◽  
Sintering Temperature

Microstructure and Properties of Spark Plasma Sintering AlN/BN Ceramics

2006 ◽  
Vol 313 ◽  
pp. 105-108 ◽  
Author(s):  
Lian Meng Zhang ◽  
Mei Juan Li ◽  
Qiang Shen ◽  
T. Li ◽  
M.Q. Yu
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Mechanical Strength ◽  
Spark Plasma Sintering ◽  
Volume Fraction ◽  
Sintering Temperature ◽  
Composite Ceramics ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Full Densification

Aluminum nitride-boron nitride (AlN/BN) composite ceramics were prepared by spark plasma sintering (SPS). The sintering behaviors of AlN/BN composites with 5~15% volume fraction of BN were studied. The influences of BN content, as well as the sintering temperature on the density, microstructure, mechanical strength, thermal conductivity and machinability of the composites were also investigated. The results showed that the full densification of AlN/BN composite ceramics could be realized by SPS technique at the temperature no higher than 1800°C for 3 minutes. The thermal conductivity of AlN/BN composites is in the range of 66~79W/mK, and AlN/BN composites can be cut or drilled by carbides or even steel tools when BN content is 15% volume fraction. The mechanical strength of AlN/BN composites is about 330MPa and is not remarkably affected by the addition of BN. The improvement of mechanical properties of AlN/BN composite ceramics is due to the fine and homogenous microstructure developed in the SPS process.

Production and Properties of Polypropylene Track Membranes

1997 ◽  
Vol 62 (5) ◽  
pp. 752-760 ◽  
Author(s):  
Lyubov I. Kravets ◽  
Sergei N. Dmitriev ◽  
Pavel Yu. Apel
Keyword(s):  
Thermal Stability ◽  
Physicochemical Properties ◽  
Mechanical Strength ◽  
Polymer Films ◽  
Heavy Ions ◽  
Physicochemical Treatment ◽  
Pore Sizes ◽  
High Homogeneity ◽  
Track Membranes ◽  
Resistance To Oxidation

This paper describes results of the method of manufacturing the polypropylene track membranes produced by physicochemical treatment under irradiation of accelerated heavy ions of polymer films. The developed method allows to produce membranes with pores of 0.1-0.2 μm in diameter and more, with an improved structural and physicochemical properties. Polypropylene track membranes of a novel sample are characterized by high homogeneity of pore sizes in magnitude, considerable mechanical strength, advanced thermal stability and resistance to oxidation in aggressive media. It opens new fields for their usage.

Association of biomass production and canopy spectral reflectance indices in winter wheat

2009 ◽  
Vol 89 (3) ◽  
pp. 485-496 ◽  
Author(s):  
B. Prasad ◽  
M. A. Babar ◽  
B. F. Carver ◽  
W. R. Raun ◽  
A. R. Klatt
Keyword(s):  
Winter Wheat ◽  
Grain Yield ◽  
Water Content ◽  
Biomass Production ◽  
Spectral Reflectance ◽  
Water Based ◽  
Canopy Spectral Reflectance ◽  
Reflectance Indices ◽  
Canopy Water ◽  
Spectral Reflectance Indices

Increased biomass production could be an important criterion for future grain yield improvement in wheat (Triticum aestivum L.). Quick assessment of genetic variations for biomass production may become a useful tool for wheat breeders. The potential of using canopy spectral reflectance indices (SRI) to assess genetic variation for biomass production in winter wheat was evaluated. Three experiments were conducted for 2 yr (2003-2004 and 2004-2005) at Oklahoma State University, Stillwater, OK. The first experiment consisted of 25 winter wheat cultivars, and the other two experiments contained two sets of 25 F4:6 and F4:7 recombinant inbred lines from two crosses developed by breeding programs in the great plains of the United States of America. Three groups of SRI (vegetation-based, pigment-based, and water-based) were tested for their ability to assess biomass production at three growth stages (booting, heading, and grainfilling). The water index and the normalized water indices gave stronger genetic correlations (P < 0.01) and linear relationship for biomass production compared with the vegetation-based and pigment-based indices. The strong association of water-based indices with biomass was related to the canopy water content of the genotypes. Canopy water content was significantly (P < 0.05) correlated with biomass production. A strong positive association (P < 0.05) of grain yield and dry biomass was observed at the heading and grainfilling stages. Our study demonstrated the potential of using water-based SRI as a breeding tool to estimate genetic variability and identify genotypes with higher biomass production, and could eventually help to achieve higher grain yield in winter wheat. Key words: Wheat; biomass; grain yield; spectral reflectance index

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