نتایج جستجو برای: porosity

تعداد نتایج: 17953  

2008
Shufang Jiang Yaohu Kang Zeqiang Sun

Measurements of porosity and pore size distribution provide important data on the physical properties of soils. This paper presents a digital image method for the analysis of soil pores. In the analysis of soil thin sections, the image threshold separating pore space from the surrounding solid, as well as the capillary pore size threshold separating air pores and capillary pores, was obtained b...

Journal: :Journal of materials science. Materials in medicine 2015
Caroline Öhman Johanna Unosson Elin Carlsson Maria Pau Ginebra Cecilia Persson Håkan Engqvist

The porosity of calcium phosphate cements has an impact on several important parameters, such as strength, resorbability and bioactivity. A model to predict the porosity for biomedical cements would hence be a useful tool. At the moment such a model only exists for Portland cements. The aim of this study was to develop and validate a first porosity prediction model for calcium phosphate cements...

2004
A. Buchel

A study of the i-layer porosity as a function of the deposition parameters by PECVD technique, is presented here. It is demonstrated in particular, that for a fixed deposition rate of 2 Ays, increasing the plasma power tends to increase the layer ̊ density, while increasing the pressure tends to increase the layer porosity. Regarding the cells, no correlation between the layer density and the in...

Journal: :Biomaterials 2006
Sylvain Deville Eduardo Saiz Antoni P Tomsia

Although extensive efforts have been put into the development of porous scaffolds for bone regeneration, with encouraging results, all porous materials have a common limitation: the inherent lack of strength associated with porosity. Hence, the development of porous hydroxyapatite scaffolds has been hindered to non-load bearing applications. We report here how freeze casting can be applied to s...

2015
Marcelo M. Oliveira Carlos Driemeier Antonio A. S. Curvelo

Nanoscale porosity is critical for cellulose reactivity and can be detrimentally affected by wet pressing. The present study evaluated how wet pressing reduced the nanoscale porosity of a set of pulps produced from sugarcane bagasse. The pulps were produced using hydrothermal treatments, followed by either 160 °C alkaline (sodium hydroxide) or 190 °C organosolv (ethanol-water) pulping. Pulping ...

2011
P. Szymczak

A reactive fluid dissolving the surrounding rock matrix can trigger an instability in the dissolution front, leading to spontaneous formation of pronounced channels or wormholes. Theoretical investigations of this instability have typically focused on a steadily propagating dissolution front that separates regions of high and low porosity. In this paper we show that this is not the only possibl...

Journal: :Blood 2014
Joshua N Farr Wei Zhang Shaji K Kumar Richard M Jacques Alvin C Ng Louise K McCready S Vincent Rajkumar Matthew T Drake

Patients with monoclonal gammopathy of undetermined significance (MGUS) are at increased fracture risk, and we have previously shown that MGUS patients have altered trabecular bone microarchitecture compared with controls. However, there are no data on whether the porosity of cortical bone, which may play a greater role in bone strength and the occurrence of fractures, is increased in MGUS. Thu...

2017
Michiko Sakamoto Toshio Matsumoto

Hydroxyapatite ceramics (HAp) have been used as bone graft materials, due to their excellent biocompatibility and osteoconductivity. Moreover, they had a wide range of porosity for using various bone defect parts. For example, HAp from 0 to 15 % porosity with high strength was useful as an ilium spacer, intervertebral spacer which requires high strength. HAp from 30 to 40% porosity was useful a...

2015
Chrystalleni Hadjicharalambous Oleg Prymak Kateryna Loza Ales Buyakov Sergei Kulkov Maria Chatzinikolaidou

It is acknowledged that cellular responses are highly affected by biomaterial porosity. The investigation of this effect is important for the development of implanted biomaterials that integrate with bone tissue. Zirconia and alumina ceramics exhibit outstanding mechanical properties and are among the most popular implant materials used in orthopedics, but few data exist regarding the effect of...

2004
R. Bachrach N. Dutta

Porosity and saturation are fundamental sedimentary properties that affect both seismic wave propagation and appraisal development and production of an oil field. Traditionally, these parameters have been estimated from seismic impedances and velocities using Biot-Gassman theory and/or or porosity-velocity relationships. However, when using theory to relate surface seismic attributes to reservo...

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