89 research outputs found
Brain Tumor Vascular Network Segmentation from Micro-Tomography
Micro-tomography produces high resolution images of bio- logical structures such as vascular networks. In this paper, we present a new approach for segmenting vascular network into pathological and normal regions from considering their micro-vessel 3D structure only. We define and use a condi- tional random field for segmenting the output of a watershed algorithm. The tumoral and normal classes are thus character- ized by their respective distribution of watershed region size interpreted as local vascular territories
Vascular network segmentation: an unsupervised approach
Micro-tomography produces high resolution images of biological structures such as vascular networks. In this paper, we present a new approach for segmenting vascular network into pathological and normal regions from considering their micro-vessel 3D structure only. We consider a partition of the volume obtained by a watershed algorithm based on the distance from the nearest vessel. Each territory is characterized by its volume and the local vascular density. The volume and density maps are first regularized by minimizing the total variation. Then, a new approach is proposed to segment the volume from the two previous restored images based on hypothesis testing. Results are presented on 3D micro-tomographic images of the brain micro-vascular network
Microstructural investigation of hybrid CAD/CAM restorative dental materials by micro-CT and SEM
Objectives: An increasing number of CAD/CAM (computer-aided
design/computer-aided manufacturing) hybrid materials have been introduced to
the dental market in recent years. In addition, CAD/CAM hybrid materials for
additive manufacturing (AM) are becoming more attractive in digital dentistry.
Studies on material microstructures using micro-computed tomography (-CT)
combined with scanning electron microscopy (SEM) have only been available to a
limited extent so far.
Methods: One CAD/CAM three-dimensional- (3D-) printable hybrid material
(VarseoSmile Crown plus) and two CAD/CAM millable hybrid materials (Vita
Enamic; Voco Grandio), as well as one direct composite material (Ceram.x duo),
were included in the present study. Cylindrical samples with a diameter of 2 mm
were produced from each material and investigated by means of synchrotron
radiation -CT at a voxel size of 0.65 m. Different samples from the
same materials, obtained by cutting and polishing, were investigated by SEM.
Results: The 3D-printed hybrid material showed some agglomerations and a more
irregular distribution of fillers, as well as a visible layered macrostructure
and a few spherical pores due to the printing process. The CAD/CAM millable
hybrid materials revealed a more homogenous distribution of ceramic particles.
The direct composite material showed multiple air bubbles and microstructural
irregularities based on manual processing.
Significance: The -CT and SEM analysis of the materials revealed
different microstructures even though they belong to the same class of
materials. It could be shown that -CT and SEM imaging are valuable tools
to understand microstructure and related mechanical properties of materials.Comment: 22 pages, 3 tables, 11 figures including supplementary materia
Computational Model for Predicting Particle Fracture During Electrode Calendering
In the context of calling for low carbon emissions, lithium-ion batteries
(LIBs) have been widely concerned as a power source for electric vehicles, so
the fundamental science behind their manufacturing has attracted much attention
in recent years. Calendering is an important step of the LIB electrode
manufacturing process, and the changes it brings to the electrode
microstructure and mechanical properties are worth studying. In this work, we
reported the observed cracking of active material (AM) particles due to
calendering pressure under ex situ nano-X-ray tomography experiments. We
developed a 3D-resolved discrete element method (DEM) model with bonded
connections to physically mimic the calendering process using real AM particle
shapes derived from the tomography experiments. The DEM model can well predict
the change of the morphology of the dry electrode under pressure, and the
changes of the applied pressure and porosity are consistent with the
experimental values. At the same time, the model is able to simulate the
secondary AM particles cracking by the fracture of the bond under force. Our
model is the first of its kind being able to predict the fracture of the
secondary particles along the calendering process. This work provides a tool
for guidance in the manufacturing of optimized LIB electrodes
Exploiting synchrotron X-ray tomography for a novel insight into flax-fibre defects ultrastructure
Flax fibres are valuable reinforcements for tomorrow's composites. However,
defects called kink-bands, which mainly appear on fibres during the extraction
and transformation phases, might affect their mechanical properties. Defects
induced pores, within the kink-band are investigated in this work. They were
morphologically explored using synchrotron phase-contrast X-ray
microtomography, a technique that displays a sharp 3D representation of the
pores. The study highlights the link between kink-bands and secondary cell wall
ultrastructure. Pores are organised concentrically around the lumen, and their
low thickness suggest that they are located at the interface between cellulose
layers within S2 (G) layer. Moreover, the pores inclination with reference to
the lumen axis follows the typical microfibrillar angle changes observed in the
literature in the kink-band region. The volumes of the pores were measured, and
a local increase in porosity was revealed in zones where defects are most
severe along the fibre.Comment: 12 pages, 6 figures. Accepted for publication in Industrial Crops and
Products (ISSN 0926-6690
Финансовая грамотность людей предпенсионного возраста как инструмент повышения их благосостояния
Объект исследования: социально-экономические процессы, имеющие причинно-следственные связи с финансовой грамотностью граждан предпенсионного возраста.
Предмет исследования: система отношений, возникающих в процессе формирования финансовой грамотности граждан предпенсионного возраста.
Цель работы: критический анализ современного опыта формирования финансовой грамотности людей предпенсионного возраста и разработка рекомендаций по повышению ее уровня.
Практическая значимость работы заключается в перспективах практического применении предлагаемых рекомендаций, направленных на повышение финансовой грамотности граждан предпенсионного возраста.Object of research: are socio-economic processes that have causal relationships with the financial literacy of citizens of pre-retirement age.
The subject of the research is: the system of relations arising in the process of forming the financial literacy of citizens of pre-retirement age.
The purpose of the final qualification work: a critical analysis of the modern experience in the formation of financial literacy of people of pre-retirement age and the development of recommendations for increasing its level.
The practical significance of the work lies in the prospects for the practical application of the proposed recommendations aimed at increasing the financial literacy of citizens
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