scholarly journals Determination of the Entire Stent Surface Area by a New Analytical Method

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5633
Author(s):  
Muhammad Saqib ◽  
Ricardo Bernhardt ◽  
Markus Kästner ◽  
Natalia Beshchasna ◽  
Gianaurelio Cuniberti ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Surface Area ◽  
Complex Geometry ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Laser Material Processing ◽  
Artery Disease ◽  
Stent Surface

Stenting is a widely used treatment procedure for coronary artery disease around the world. Stents have a complex geometry, which makes the characterization of their corrosion difficult due to the absence of a mathematical model to calculate the entire stent surface area (ESSA). Therefore, corrosion experiments with stents are mostly based on qualitative analysis. Additionally, the quantitative analysis of corrosion is conducted with simpler samples made of stent material instead of stents, in most cases. At present, several methods are available to calculate the stent outer surface area (SOSA), whereas no model exists for the calculation of the ESSA. This paper presents a novel mathematical model for the calculation of the ESSA using the SOSA as one of the main parameters. The ESSA of seven magnesium alloy stents (MeKo Laser Material Processing GmbH, Sarstedt, Germany) were calculated using the developed model. The calculated SOSA and ESSA for all stents are 33.34%(±0.26%) and 111.86 mm (±0.85 mm), respectively. The model is validated by micro-computed tomography (micro-CT), with a difference of 12.34% (±0.46%). The value of corrosion rates calculated using the ESSA computed with the developed model will be 12.34% (±0.46%) less than that of using ESSA obtained by micro-CT.

scholarly journals Measuring specific surface area of snow by near-infrared photography

2006 ◽  
Vol 52 (179) ◽  
pp. 558-564 ◽  
Author(s):  
Margret Matzl ◽  
Martin Schneebeli
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Near Infrared ◽  
Two Dimensions ◽  
Chemical Models ◽  
Snow Stratigraphy ◽  
Physical And Chemical

AbstractThe specific surface area (SSA) is considered an essential microstructural parameter for the characterization of snow. Photography in the near-infrared (NIR) spectrum is sensitive to the SSA. We calculated the snow reflectance from calibrated NIR images of snow-pit walls and measured the SSA of samples obtained at the same locations. This new method is used to map the snow stratigraphy. The correlation between reflectance and SSA was found to be 90%. Calibrated NIR photography allows quantitative determination of SSA and its spatial variation in a snow profile in two dimensions within an uncertainty of 15%. In an image covering 0.5–1.0 m2, even layers of 1mm thickness can be documented and measured. Spatial maps of SSA are an important tool in initializing and validating physical and chemical models of the snowpack.

STUDY PORE CHARACTERIZATION OF γ-ALUMINA – ACTIVATED CARBON COMPOSITE MADE OF CASSAVA PEELS (Manihot esculenta Cranz)

2015 ◽  
Vol 11 (1) ◽  
pp. 47
Author(s):  
Hartini Hartini ◽  
Yuniawan Hidayat ◽  
Mudjijono Mudjijono
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Total Pore Volume ◽  
Carbon Composite ◽  
Bet Method ◽  
Industrial Standards ◽  
Cassava Peels ◽  
Made In

<p>A composite of γ-alumina and activated carbon made of cassava peels was studied in terms of its pore structures and its properties. The objective of this study was to determine the interaction and structure, as well as the character and pore size of γ-alumina – activated carbon composite.</p><p>Carbon made of cassava peels was activated by H<sub>2</sub>SO<sub>4</sub> and its activities were tested according to the Indonesian Industrial Standards (SII). The addition of activated carbon into γ-alumina made in variations of 10, 20, 30, 40 and 50 % w/w, of the total weight of 10 grams. The composite of γ-alumina - activated carbon was characterized by FTIR, SAA (Surface Area Analyzer), XRD, and determination of Hysteresis Loop composites.</p>The greater addition of activated carbon to γ-alumina causes intermolecular interactions between –O-H groups form rehydrated hydrogen bonds in the composite is greater. The structure of γ-alumina in the composites remain intact although the percentage of activated carbon in composite is large. The total pore volume and surface area using the BET method of the composite decreases with increasing activated carbon percentage. The greater addition of activated carbon to γ-alumina causes size of mesoporous composites decreased with the characteristic of a composite formed is closer to the activated carbon.

scholarly journals Longitudinal in vivo micro-CT-based approach allows spatio-temporal characterization of fracture healing patterns and assessment of biomaterials in mouse femur defect models

2020 ◽  
Author(s):  
Esther Wehrle ◽  
Duncan C Tourolle né Betts ◽  
Gisela A Kuhn ◽  
Erica Floreani ◽  
Malavika H Nambiar ◽  
...  
Keyword(s):  
Bone Regeneration ◽  
Healing Process ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Collagen Scaffolds ◽  
Non Union ◽  
Spatio Temporal ◽  
Large Bone

AbstractThorough preclinical evaluation of novel biomaterials for treatment of large bone defects is essential prior to clinical application. Using in vivo micro-computed tomography (micro-CT) and mouse femoral defect models with different defect sizes, we were able to detect spatio-temporal healing patterns indicative of physiological and impaired healing in three defect sub-volumes and the adjacent cortex. The time-lapsed in vivo micro-CT-based approach was then applied to evaluate the bone regeneration potential of biomaterials using collagen and BMP-2 as test materials. Both collagen and BMP-2 treatment led to distinct changes in bone turnover in the different healing phases. Despite increased periosteal bone formation, 87.5% of the defects treated with collagen scaffolds resulted in non-unions. Additional BMP-2 application significantly accelerated the healing process and increased the union rate to 100%. This study further shows potential of time-lapsed in vivo micro-CT for capturing spatio-temporal deviations preceding non-union formation and how this can be prevented by application of biomaterials.This study therefore supports the application of longitudinal in vivo micro-CT for discrimination of normal and disturbed healing patterns and for the spatio-temporal characterization of the bone regeneration capacity of biomaterials.

Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bones. Geometrical parameters depend on scanning resolutions

2016 ◽  
Vol 340 ◽  
pp. 127-134 ◽  
Author(s):  
Olivier Cros ◽  
Hans Knutsson ◽  
Mats Andersson ◽  
Elin Pawels ◽  
Magnus Borga ◽  
...  
Keyword(s):  
Surface Area ◽  
Ct Scanning ◽  
Geometrical Parameters ◽  
Micro Ct ◽  
Temporal Bones ◽  
Area And Volume

scholarly journals The Study of Specific Surface Area from Carbonat Rock Using Micro Computed Tomography (µ-CT)

2017 ◽  
Vol 1 ◽  
pp. 111-113
Author(s):  
Mahendra Risky Habibi ◽  
Thaqibul Fikri Niyartama
Keyword(s):  
Computed Tomography ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Calculation Result ◽  
Carbonate Rocks ◽  
Programming Algorithm ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
The Difference

Carbonate rocks have been scanned and reconstructed in order to get the value of specific surface area. We get it from the reservoir at a depth of 1000 metres in South Sumatra. Skyscan Micro-CT 1173 is used for throwing and thresholding images using Global Otshu to characterize rocks. Our calculation result shows that the value of specific surface area of carbonate rocks show results 100 to 10-2 using the programming Algorithm Fuzzy C-Mean. The difference in values far enough that it can be assumed that the carbonate rocks have a heterogeneous surface area. In addition, histogram model shows the similarity of the sample. The macro sample has the same characteristics as the micro sample.

scholarly journals INTERCALATION OF OLYGOMER OF HYDROXYL-CHROMIUM INTO NATURAL KAOLINITE

2010 ◽  
Vol 8 (1) ◽  
pp. 31-36
Author(s):  
Rodiansono Rodiansono ◽  
Reda Ariyantie ◽  
Abdullah Abdullah
Keyword(s):  
Surface Area ◽  
Pore Radius ◽  
Nitrate Solution ◽  
Chemical Properties ◽  
Basal Spacing ◽  
Physico Chemical ◽  
Ft Ir ◽  
N2 Sorption

Preparation of a kaolin-hydroxyl chromium composite and characterization of its physico-chemical properties were conducted. The olygomer hydroxyl-chromium was prepared by adding Na2CO3 to 0.1 M chromium nitrate solution (ratio OH/Cr = 2) and then dried at 110 oC and 400 oC for 4 h. Characterization of kaolin-hydroxyl chromium composite includes determination of acidity, functional groups, basal spacing, and surface area (BET-N2 sorption analyzer). The result showed that intercalation of hydroxyl chromium resulted in the decreasing of basal spacing but increased the specific surface area of kaolin. Drying of the intercalated kaolin at 400 oC decreased surface area, total volume pore and pore radius. FT-IR spectra showed that hydroxyl-chromium detected at wavelength of 2925 and 2855 cm-1.   Keywords: natural kaolin, intercalation, olygomer hydroxyl-chromium, kaolin-hydroxyl chromium composite

scholarly journals Spectral X-ray computed micro tomography: a tool for 3-dimensional chemical imaging

2021 ◽  
Author(s):  
Jonathan Sittner ◽  
Margarita Merkulova ◽  
Jose Ricardo da Assuncao Godinho ◽  
Axel Renno ◽  
Veerle Cnudde ◽  
...  
Keyword(s):  
Chemical Imaging ◽  
Drill Core ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
X Ray ◽  
3 Dimensional ◽  
X Ray Computed ◽  
Micro Tomography ◽  
3D Information

&lt;p&gt;Image-based analytical tools in geosciences are indispensable for the characterization of minerals, but most of them are limited to the surface of a polished plane in a sample and lack 3D information. X-ray micro computed tomography (micro CT) provides the missing 3D information of the microstructures inside samples. However, a major drawback of micro CT in the characterization of minerals is the lack of chemical information that makes mineral classification challenging.&lt;/p&gt;&lt;p&gt;Spectral X-ray micro computed tomography (Sp-CT) is a new and evolving tool in different applications such as medicine, security, material science, and geology. This non-destructive method uses a multi-pixel photon-counting detector (PCD) such as cadmium telluride (CdTe) in combination with a conventional CT scanner (TESCAN CoreTOM) to image a sample and detect its transmitted polychromatic X-ray spectrum. Based on the spectrum, elements in a sample can be identified by an increase in attenuation at specific K-edge energies. Therefore, chemically different particles can be distinguished inside a sample from a single CT scan. The method is able to distinguish elements with K-edges in the range from 25 to 160 keV, which applies to elements with Z &gt; 48 (Sittner et al., 2020).&lt;/p&gt;&lt;p&gt;We present results from various sample materials. Different pure elements and element oxides were measured to compare the position of theoretical and measured K-edge energies. All measured K-edge energies are slightly above the theoretical value, but based on the results a correction algorithm could be developed. Furthermore, different monazite grains were investigated, which can be divided into two groups with respect to the content of different RE elements on the basis of the spectrum: La-Ce-rich and La-Ce-poor. In addition, samples from the Au-U Witwatersrand Supergroup demonstrate the potential applications of Sp-CT for geological samples. We measured different drill core samples from the Kalkoenkrans Reef at the Welkom Gold field. Sp-CT can distinguish gold, uraninite and galena grains based on their K-edge energies in the drill core without preparation.&lt;/p&gt;&lt;p&gt;Sittner, J., Godinho, J. R. A., Renno, A. D., Cnudde, V., Boone, M., De Schryver, T., Van Loo, D., Merkulova, M., Roine, A., &amp; Liipo, J. (2020). Spectral X-ray computed micro tomography: 3-dimensional chemical imaging. X-Ray Spectrometry, September, 1&amp;#8211;14.&lt;/p&gt;

scholarly journals STUDY PORE CHARACTERIZATION OF γ-ALUMINA – ACTIVATED CARBON COMPOSITE MADE OF CASSAVA PEELS (Manihot esculenta Cranz)

2016 ◽  
Vol 11 (1) ◽  
pp. 47
Author(s):  
Hartini Hartini ◽  
Yuniawan Hidayat ◽  
Mudjijono Mudjijono
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Total Pore Volume ◽  
Carbon Composite ◽  
Bet Method ◽  
Industrial Standards ◽  
Cassava Peels ◽  
Made In

<p>A composite of γ-alumina and activated carbon made of cassava peels was studied in terms of its pore structures and its properties. The objective of this study was to determine the interaction and structure, as well as the character and pore size of γ-alumina – activated carbon composite.</p><p>Carbon made of cassava peels was activated by H<sub>2</sub>SO<sub>4</sub> and its activities were tested according to the Indonesian Industrial Standards (SII). The addition of activated carbon into γ-alumina made in variations of 10, 20, 30, 40 and 50 % w/w, of the total weight of 10 grams. The composite of γ-alumina - activated carbon was characterized by FTIR, SAA (Surface Area Analyzer), XRD, and determination of Hysteresis Loop composites.</p>The greater addition of activated carbon to γ-alumina causes intermolecular interactions between –O-H groups form rehydrated hydrogen bonds in the composite is greater. The structure of γ-alumina in the composites remain intact although the percentage of activated carbon in composite is large. The total pore volume and surface area using the BET method of the composite decreases with increasing activated carbon percentage. The greater addition of activated carbon to γ-alumina causes size of mesoporous composites decreased with the characteristic of a composite formed is closer to the activated carbon.

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