scholarly journals Micro-CT analysis of the Caribbean octocoral Eunicea flexuosa subjected to elevated pCO2

2015 ◽  
Vol 73 (3) ◽  
pp. 910-919 ◽  
Author(s):  
I. C. Enochs ◽  
D. P. Manzello ◽  
H. H. Wirshing ◽  
R. Carlton ◽  
J. Serafy
Keyword(s):  
Marine Biota ◽  
Micro Computed Tomography ◽  
Precipitate Calcium Carbonate ◽  
Anthropogenic Carbon ◽  
Coral Reef Ecosystems ◽  
Ct Analysis ◽  
Caribbean Coral Reefs ◽  
The Common ◽  
The Caribbean ◽  
Apical Section

AbstractRising anthropogenic carbon dioxide has resulted in a drop in ocean pH, a phenomenon known as ocean acidification (OA). These acidified waters have many ramifications for diverse marine biota, especially those species which precipitate calcium carbonate skeletons. The permanence of coral reef ecosystems is therefore closely related to OA stress as habitat-forming corals will exhibit reduced calcification and growth. Relatively little is known concerning the fate of other constituent taxa which may either suffer concomitant declines or be competitively favoured in acidified waters. Here, we experimentally (49 d) test the effects of next century predictions for OA (pH = 7.75, pCO2 = 1081 µatm) vs. near-present-day conditions (pH = 8.01, pCO2 = 498 µatm) on the common Caribbean octocoral Eunicea flexuosa. We measure linear extension of this octocoral and use a novel technique, high-resolution micro-computed tomography, to measure potential differences in the morphology of calcified internal skeletal structures (sclerites) in a 2 mm apical section of each branch. Despite the use of highly accurate procedures, we found no significant differences between treatments in either the growth of E. flexuosa branches or the structure of their sclerites. Our results suggest a degree of resilience to OA stress and provide evidence that this octocoral species may persist on Caribbean coral reefs, despite global change.

scholarly journals One Hundred and Fifty Years of Warming on Caribbean Coral Reefs

2021 ◽  
Author(s):  
Colleen B Bove ◽  
Laura Mudge ◽  
John F Bruno
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Thermal Characteristics ◽  
Marine Systems ◽  
Caribbean Coral ◽  
Coral Reef Ecosystems ◽  
Caribbean Coral Reef ◽  
Caribbean Coral Reefs ◽  
The Caribbean ◽  
And Function

Anthropogenic climate change is rapidly altering the characteristics and dynamics of biological communities. This is especially apparent in marine systems as the world's oceans are warming at an unprecedented rate, causing dramatic changes to coastal marine systems, especially on coral reefs of the Caribbean. We used three complementary ocean temperature databases (HadISST, Pathfinder, and OISST) to quantify change in thermal characteristics of Caribbean coral reefs over the last 150 years (1871-2020). These sea surface temperature (SST) databases included combined in situ and satellite-derived SST (HadISST, OISST), as well as satellite-only observations (Pathfinder) at multiple spatial resolutions. We also compiled a Caribbean coral reef database identifying 5,326 unique reefs across the region. We found that Caribbean reefs have warmed on average by 0.20 °C per decade since 1987, the calculated year that rapid warming began on Caribbean reefs. Further, geographic variation in warming rates ranged from 0.17 °C per decade on Bahamian reefs to 0.26 °C per decade on reefs within the Southern and Eastern Caribbean ecoregions. If this linear rate of warming continues, these already threatened ecosystems would warm by an additional 1.6 °C on average by 2100. We also found that marine heatwave (MHW) events are increasing in both frequency and duration across the Caribbean. Caribbean coral reefs now experience on average 5 MHW events annually, compared to 1 per year in the early 1980s. Combined, these changes have caused a dramatic shift in the composition and function of Caribbean coral reef ecosystems. If reefs continue to warm at this rate, we are likely to lose even the remnant Caribbean coral reef communities of today in the coming decades.

scholarly journals A Micro-Computed Tomography Comparison of the Porosity in Additively Fabricated CuCr1 Alloy Parts Using Virgin and Surface-Modified Powders

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1995
Author(s):  
Mirko Sinico ◽  
Suraj Dinkar Jadhav ◽  
Ann Witvrouw ◽  
Kim Vanmeensel ◽  
Wim Dewulf
Keyword(s):  
High Energy ◽  
High Energy Density ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Powder Bed ◽  
Metallurgical Defects ◽  
Ct Analysis ◽  
Ct Data ◽  
Surface Modified ◽  
Fusion Pores

Recently, the use of novel CuCr1 surface-modified powder for reliable laser powder-bed fusion (LPBF) manufacturing has been proposed, enabling a broader LPBF processing window and longer powder storage life. Nevertheless, virgin CuCr1 powder is also LPBF processable, on the condition that a high-energy density is employed. In this work, we compare two dense specimens produced from virgin and surface-modified CuCr1 powder. Furthermore, a third sample fabricated from surface-modified powder is characterized to understand an abnormal porosity content initially detected through Archimedes testing. Utilizing high-resolution micro-CT scans, the nature of the defects present in the different samples is revealed. Pores are analyzed in terms of size, morphology and spatial distribution. The micro-CT data reveal that the virgin CuCr1 dense specimen displays keyhole pores plus pit cavities spanning multiple layer thicknesses. On the other hand, the sample fabricated with the surface-modified CuCr1 powder mainly contains small and spherical equi-distributed metallurgical defects. Finally, the CT analysis of the third specimen reveals the presence of a W contamination, favoring lack-of-fusion pores between subsequent LPBF layers. The LPBF melting mode (keyhole or conductive), the properties of the material, and the potential presence of contaminants are connected to the different porosity types and discussed.

scholarly journals 3D Ore Characterization as a Paradigm Shift for Process Design and Simulation in Mineral Processing

2021 ◽  
Author(s):  
Pratama Istiadi Guntoro ◽  
Yousef Ghorbani ◽  
Jan Rosenkranz
Keyword(s):  
Process Design ◽  
Paradigm Shift ◽  
Mineral Processing ◽  
Analysis Tool ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Automated Mineralogy ◽  
Process Mineralogy ◽  
The Common ◽  
Ore Characterization

AbstractCurrent advances and developments in automated mineralogy have made it a crucial key technology in the field of process mineralogy, allowing better understanding and connection between mineralogy and the beneficiation process. The latest developments in X‑ray micro-computed tomography (µCT) have shown a great potential to let it become the next-generation automated mineralogy technique. µCT’s main benefit lies in its capability to allow 3D monitoring of the internal structure of the ore sample at resolutions down to a few hundred nanometers, thus excluding the common stereological error in conventional 2D analysis. Driven by the technological and computational progress, µCT is constantly developing as an analysis tool and successively it will become an essential technique in the field of process mineralogy. This study aims to assess the potential application of µCT systems, for 3D ore characterization through relevant case studies. The opportunities and platforms that µCT 3D ore characterization provides for process design and simulation in mineral processing are presented.

scholarly journals Les catastrophes naturelles dans les romans caribéens d’expression française

Il Tolomeo ◽  
2020 ◽  
Author(s):  
Alessia Vignoli
Keyword(s):  
Native Americans ◽  
Natural Hazards ◽  
Caribbean Literature ◽  
Common Origin ◽  
Caribbean Region ◽  
Common Features ◽  
African Slaves ◽  
European Colonization ◽  
The Common ◽  
The Caribbean

The notion of ‘disaster’ pervades the Caribbean thought. The common origin of the Caribbean region, the European colonization, caused two disasters: the extermination of Native Americans and the deportation of African slaves. The union between nature and the oppressed people against the oppressor resulted in the creation of an environmental conscience that the Caribbean literature has often expressed. This essay will investigate the common points shared by some Haitian, Martinican and Guadeloupean authors in the writing of natural hazards. It will show that, despite the diversity that marks the Caribbean, there is a repetition of common features that proves its geopoetic unity.

Quantitative micro-computed tomography analysis and rheological investigation of Nitrile rubber/Rockwool composites

2021 ◽  
pp. 002199832110338
Author(s):  
Elisson BD da Rocha ◽  
Ana Maria F de Sousa ◽  
Ana Lúcia N da Silva ◽  
Cristina RG Furtado ◽  
Marcos V Colaço ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Elastic Modulus ◽  
Aspect Ratio ◽  
Volume Fraction ◽  
Nitrile Rubber ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Rubber Composites ◽  
Ratio Data ◽  
Ct Analysis

This study reports the reinforcement degree investigation of two types of rockwool fibers (F1 and F2), in nitrile rubber composites. The micro-computed tomography (micro-CT) 3D images showed that both fibers were well-dispersed in the NBR matrix, without a preferential orientation. The micro-CT analysis also allowed quantifying volume fraction, inter-fiber distance, and aspect ratio. Those morphometric parameters were used for supporting the composites rheological behavior assessment. Changes in the elastic modulus and phase angle followed the same trend of the inter-fiber distance values, regardless the type of fiber. Both volume fraction and aspect ratio data from the micro-CT analysis were used to predict theoretical values of elastic modulus using the Guth-Gold and modified Guth-Gold equations, and the results obtained were compared to the rheological experimental data. This analysis was helpful to better understand the rockwool fibers reinforcement degree differences in the production of the nitrile rubber composites.

scholarly journals Impact of DBBM Fragments on the Porosity of the Calvarial Bone: A Pilot Study on Mice

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4748
Author(s):  
Ulrike Kuchler ◽  
Patrick Heimel ◽  
Alexandra Stähli ◽  
Franz Josef Strauss ◽  
Bernadette Luza ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Histological Evaluation ◽  
Random Allocation ◽  
Bovine Bone ◽  
Distribution Analysis ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Calvarial Bone ◽  
Ct Analysis ◽  
Bovine Bone Mineral

Deproteinized bovine bone mineral (DBBM) is brittle and can break into fragments. Here, we examined whether DBBM fragments have an impact on mice calvarial bone during bone augmentation. DBBM was either randomly crushed (DBBM fragments) or left undisturbed (DBBM granules). Then, DBBM fragments or original DBBM granules were placed onto calvarial bone in 20 BALB/c mice. Following random allocation, ten mice received DBBM fragments and ten mice received original DBBM granules. After fourteen days of healing, micro computed tomography (micro-CT) and histological analysis of the augmented sites were performed. The primary outcome was the porosity of the calvarial bone. The micro-CT analysis revealed that DBBM fragments failed to significantly change the porosity of the calvarial bone as compared with original DBBM granules, despite the slightly higher bone resorption in the DBBM fragment group, 10.3% (CI 6.3–11.6) versus 6.1% (CI 4.1–7.8, p = 0.355), respectively. The cortical bone volume was not altered by DBBM fragments as compared with original DBBM granules, i.e., 79.0% (CI 78.9–81.2) versus 81.5% (CI 80.1–83.3, p = 0.357), respectively. The DBBM fragment group revealed similar bone thickness values as compared with the DBBM granules group, i.e., 0.26 mm (CI 0.23–0.29) versus 0.25 mm (CI 0.22–0.27, p = 0.641), respectively. The histological evaluation supported the micro-CT observations, displaying minor signs of porosity and resorption. The particle-size distribution analysis confirmed a shift towards smaller particle sizes in the DBBM fragment group. These findings suggest that DBBM fragments behave similarly to original DBBM granules in terms of bone morphological changes at augmented sites.

scholarly journals DEVELOPING THE COMMON MARMOSET AS A TRANSLATIONAL MODEL OF AGE-RELATED OSTEOARTHRITIS

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S104-S104
Author(s):  
Dennis M Minton ◽  
Angela J Marolf ◽  
Kelly S Santangelo ◽  
Adam B Salmon ◽  
Adam R Konopka
Keyword(s):  
Subchondral Bone ◽  
Bone Structure ◽  
Common Marmoset ◽  
Knee Joints ◽  
Micro Computed Tomography ◽  
Bone Thickness ◽  
Aging Research ◽  
Naturally Occurring ◽  
Age Related ◽  
The Common

Abstract Age is a primary risk factor for osteoarthritis (OA). The mechanisms that contribute to OA are poorly understood and disease modifying treatments have not been identified. A critical shortcoming in developing therapies is the limited number of translational models available to identify the causes of naturally occurring OA. Our goal is to use the common marmoset as a non-human primate (NHP) model of age-related OA. NHP are the closest evolutionary relative to humans and share many characteristics of human aging. The marmoset has advantages over other NHP for aging research because of their relatively short maximal lifespan and small size. Micro-computed tomography (uCT) was performed on whole-knee joints obtained from young (10 yrs, n=3) marmosets at necropsy. OA was evaluated using a clinical uCT scoring system and quantitative assessments of subchondral bone structure and ossified meniscal volume. Advancing age was positively correlated to increased uCT OA score (p<0.05, r=0.59 ), mainly through increased number and size of osteophytes and progressive subchondral bone sclerosis from the medial to both medial and lateral compartments. For marmosets displaying meniscal ossification, older marmosets had greater (p<0.05) ossified meniscal volume than middle-aged and younger marmosets, respectively. Trabecular (p=0.05) and cortical bone thickness (p<0.05) were also lower in older marmosets. These data are the first to indicate that the marmoset develops naturally occurring, age-related OA and support the pursuit of additional studies using the marmoset to identify OA mechanisms and test potential interventions.

scholarly journals Comparative Quality Control of Titanium Alloy Ti–6Al–4V, 17–4 PH Stainless Steel, and Aluminum Alloy 4047 Either Manufactured or Repaired by Laser Engineered Net Shaping (LENS)

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4171 ◽  
Author(s):  
Noam Eliaz ◽  
Nitzan Foucks ◽  
Dolev Geva ◽  
Shai Oren ◽  
Noy Shriki ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
High Standard ◽  
Micro Computed Tomography ◽  
Laser Engineered Net Shaping ◽  
Ct Analysis ◽  
Powder Particles ◽  
Structural Parts ◽  
Net Shaping ◽  
Roughness Measurements

Additive manufacturing attracts much interest for manufacturing and repair of structural parts for the aerospace industry. This paper presents comparative characterization of aircraft items made of Al 4047 alloy, Ti-6Al-4V alloy, and 17-4 precipitation hardened (PH) (AISI 630) stainless steel, either manufactured or repaired by laser engineered net shaping (LENS). Chemical analysis, density, and surface roughness measurements, X-ray micro-computed tomography (μ-CT) analysis, metallography, and micro-hardness testing were conducted. In all three materials, microstructures typical of rapid solidification were observed, along with high density, chemical composition, and hardness comparable to those of the counterpart wrought alloys (even in hard condition). High standard deviation in hardness values, anisotropic geometrical distortion, and overbuild at top edges were observed. The detected defects included partially melted and unmelted powder particles, porosity, and interlayer lack of fusion, in particular at the interface between the substrate plate and the build. There was a fairly good match between the density values measured by μ-CT and those measured by the Archimedes method; there was also good correlation between the type of defects detected by both techniques. Surface roughness, density of partially melted powder particles, and the content of bulk defects were significantly higher in Al 4047 than in 17-4 PH stainless steel and Ti-6Al-4V alloy. Optical gaging can be used reliably for surface roughness measurements. The implications of these findings are discussed.

Hypophosphatasia: Evaluation of Size and Mineral Density of Exfoliated Teeth

2016 ◽  
Vol 40 (6) ◽  
pp. 496-502 ◽  
Author(s):  
S Hayashi-Sakai ◽  
N Numa-Kinjoh ◽  
M Sakamoto ◽  
J Sakai ◽  
J Matsuyama ◽  
...  
Keyword(s):  
Density Distribution ◽  
Primary Teeth ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Mineral Density ◽  
Normal Range ◽  
Mean Values ◽  
Present Patient ◽  
Ct Analysis ◽  
The Mean

Objective: Most cases of hypophosphatasia (HPP) exhibit early loss of primary teeth. Results of micro-computed tomography (micro-CT) analysis of teeth with HPP have not yet been reported. The purpose of the present study was to describe the size and mineral density distribution and mapping of exfoliated teeth with HPP using micro CT. Study design: Seven exfoliated teeth were obtained from a patient with HPP. Exfoliated teeth sizes were measured on micro CT images and mineral densities of the mandibular primary central incisors were determined. Results: Partial dentures were fabricated for the patient to replace the eight primary teeth which had exfoliated. Most primary teeth sizes were within the normal range. The mean values of enamel and dentin mineral densities in teeth with HPP were 1.35 and 0.88 g/cm3, respectively, in the mandibular primary central incisors. Conclusion: Mineral density distribution and mapping revealed that the values in teeth with HPP were lower than the homonymous teeth controls in all regions from the crown to apex. Furthermore, it was demonstrated that the differences between HPP and controls were larger on the crown side and the differences tended to converge on the apex side. These results suggested that the present patient showed mild hypomineralization in the primary dentition.

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