A novel solution of deep learning for endoscopic ultrasound image segmentation: enhanced computer aided diagnosis of gastrointestinal stromal tumor

Multimedia Tools and Applications - Gastrointestinal stromal tumor is one of the critical tumors that doctors do not suggest to get frequent endoscopy, so there is a need for a diagnosis system...     

Cost estimates to guide pre-selection of processes

A process is a method of shaping, joining or surface-treating a material. Process selection has three steps. The first is to identify from the ‘menu’ of all available processes, the subset, which can give a chosen material the desired shape with the desired detail, precision and finish. The second is to choose, from among these, the ones that will do so at the lowest cost. The final step is to investigate the most promising processes in depth, exploring considerations such as availability, in-house experience, safety and environmental issues. The first two steps can be thought of as process pre-selection. Components have to be assembled and finished to create products. Here too, the ability to rank by cost, however crudely, helps guide pre-selection. Cost models are reviewed from the perspective of material and process selection. An approximate model is useful provided it has generality—that is, it must allow comparison of very different processes. Many approaches fail in this. One that works, based on resource consumption, is developed here and its use for selection is illustrated. It has been implemented as part of a tool that allows rapid pre-selection from a database of 112 processes.     

Effect of mechanical alloying time and carbon nanotube (CNT) content on the evolution of aluminum (Al)–CNT composite powders

One of the major obstacles to the effective use of carbon nanotubes as reinforcements in metal matrix composites is their agglomeration and poor distribution/dispersion within the metallic matrix. In the present work, we use mechanical alloying (MA) to mechanically mix CNT (2 and 5 wt.%) with Al powders. These powders would be used as precursors for subsequent consolidation to generate bulk CNT-Al composites. Hence controlling the initial powder characteristics prior to high temperature consolidation is important. Up to 48 h of milling was employed to investigate the effect of milling time on the particle size, morphology and CNT dispersions. The results show that particle size and morphology vary with milling time and CNT content. Also the addition of process control agents such as methanol can aid in controlling the powder characteristics.     

Effect of processing technique on the dispersion of carbon nanotubes within polypropylene carbon nanotube‐composites and its effect on their mechanical properties

Carbon nanotube‐reinforced polymer composites are being investigated as promising new materials having enhanced physical and mechanical properties. With regards to mechanical behavior, the enhancements reported thus far by researchers are lower than the theoretical predictions. One of the key requirements to attaining enhanced behavior is a uniform dispersion of the nanotubes within the polymer matrix. Although solvent mixing has been used extensively, there are concerns that any remaining solvent within the composite may degrade its mechanical properties. In this work, a comparison is carried out between solvent and “solvent‐free” dry mixing for dispersing multiwall carbon nanotubes in polypropylene before further melt mixing by extrusion. Various weight fractions of carbon nanotubes (CNTs) are added to the polymer and their effect on the mechanical properties of the resulting composites is investigated. Enhancements in yield strength, hardness, and Young's modulus when compared with the neat polymer, processed under similar conditions, are observed. Differences in mechanical properties and strain as a function of the processing technique (solvent or dry) are also clearly noted. In addition, different trends of enhancement of mechanical properties for the solvent and dry‐mixed extrudates are observed. Dry mixing produces composites with the highest yield strength, hardness, and modulus at 0.5 wt% CNT, whereas solvent mixing produces the highest mechanical properties at CNT contents of 1 wt%. It is believed that this difference is primarily dependent on the dispersion of CNTs within the polymer matrix which is influenced by the processing technique. Field emission scanning electron microscopy analysis shows the presence of clusters in large wt% CNT samples produced by dry mixing. Samples produced by solvent mixing are found to contain homogeneously distributed CNTs at all CNT wt fractions. CNT pull‐out is observed and may explain the limited enhancement in mechanical properties. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Aptamer-Aptamer Chimera for Targeted Delivery and ATP-Responsive Release of Doxorubicin into Cancer Cells

Aptamers offer a great opportunity to develop innovative drug delivery systems that can deliver cargos specifically into targeted cells. In this study, a chimera consisting of two aptamers was developed to deliver doxorubicin into cancer cells and release the drug in cytoplasm in response to adenosine-5′-triphosphate (ATP) binding. The chimera was composed of the AS1411 anti-nucleolin aptamer for cancer cell targeting and the ATP aptamer for loading and triggering the release of doxorubicin in cells. The chimera was first produced by hybridizing the ATP aptamer with its complementary DNA sequence, which is linked with the AS1411 aptamer via a poly-thymine linker. Doxorubicin was then loaded inside the hybridized DNA region of the chimera. Our results show that the AS1411–ATP aptamer chimera was able to release loaded doxorubicin in cells in response to ATP. In addition, selective uptake of the chimera into cancer cells was demonstrated using flow cytometry. Furthermore, confocal laser scanning microscopy showed the successful delivery of the doxorubicin loaded in chimeras to the nuclei of targeted cells. Moreover, the doxorubicin-loaded chimeras effectively inhibited the growth of cancer cell lines and reduced the cytotoxic effect on the normal cells. Overall, the results of this study show that the AS1411–ATP aptamer chimera could be used as an innovative approach for the selective delivery of doxorubicin to cancer cells, which may improve the therapeutic potency and decrease the off-target cytotoxicity of doxorubicin.     

Effect of carbon nanotube (CNT) content on the mechanical properties of CNT-reinforced aluminium composites

The interest in carbon nanotubes (CNTs) as reinforcements for aluminium (Al) has been growing considerably. Efforts have been largely focused on investigating their contribution to the enhancement of the mechanical performance of the composites. The uniform dispersion of CNTs in the Al matrix has been identified as being critical to the pursuit of enhanced properties. Ball milling as a mechanical dispersion technique has proved its potential. In this work, we use ball milling to disperse up to 5 wt.% CNT in an Al matrix. The effect of CNT content on the mechanical properties of the composites was investigated. Cold compaction and hot extrusion were used to consolidate the ball-milled Al–CNT mixtures. Enhancements of up to 50% in tensile strength and 23% in stiffness compared to pure aluminium were observed. Some carbide formation was observed in the composite containing 5 wt.% CNT. In spite of the observed overall reinforcing effect, the large aspect ratio CNTs used in the present study were difficult to disperse at CNT wt.% greater than 2, and thus the expected improvements in mechanical properties with increase in CNT weight content were not fully realized.     

Structure and properties of nylon 6–clay nanocomposites: effect of temperature and reprocessing

Melt-compounding is a technique which has been commonly used for producing polymer–clay nanocomposites with enhanced mechanical, thermal, and physical properties. Twin-screw extruders have been found to effectively exfoliate the clay platelets due to their high shear intensity. However, concerns about polymer and organoclay degradation have been raised in some studies. In this investigation, a composite of nylon 6–Cloisite 30B with fully exfoliated and well-dispersed clay particles was produced using a single-screw extruder and hence with limited polymer degradation. We show that processing temperature plays an important role in enhancing dispersion and that reprocessing at a higher temperature can enhance both dispersion and exfoliation and thus can result in composites with superior properties. We attempt to elucidate how the change in melt viscosity—coupled with the change in processing temperature—affects clay exfoliation and dispersion.     

Spark plasma extrusion (SPE) of ball-milled aluminum and carbon nanotube reinforced aluminum composite powders

Ball-milled aluminum (Al) and Al–carbon nanotube (CNT) composite (2.5 wt.% CNT loading) powders have been consolidated using a spark plasma extrusion (SPE) process. Compared with spark plasma sintering (SPS), SPE has the added advantages of allowing the production of powder-based materials of extended geometries and bulk deformation under the influence of electric current which may yield materials with unique properties. The process is discussed in this short communication together with resulting microstructures and properties for the investigated materials.