Search

Neoadjuvant chemotherapy (NAC) has contributed to improving breast cancer outcomes, and it would ideally reduce the need for definitive breast surgery in patients who have no residual cancer after NAC treatment. However, there is no reliable noninvasive imaging modality accepted as the routine method to assess response to NAC. Because of the inability to detect complete response, post‐NAC surgery remains the standard of care. To overcome this limitation, a single‐breath‐hold photoacoustic computed tomography (SBH‐PACT) system is developed to provide contrast similar to that of contrast‐enhanced magnetic resonance imaging, but with much higher spatial and temporal resolution and without injection of contrast chemicals. SBH‐PACT images breast cancer patients at three time points: before, during, and after NAC. The analysis of tumor size, blood vascular density, and irregularity in the distribution and morphology of the blood vessels on SBH‐PACT accurately identifies response to NAC as confirmed by the histopathological diagnosis. SBH‐PACT shows its near‐term potential as a diagnostic tool for assessing breast cancer response to systemic treatment by noninvasively measuring the changes in cancer‐associated angiogenesis. Further development of SBH‐PACT may also enable serial imaging, rather than the use of current invasive biopsies, to diagnose and follow indeterminate breast lesions. [ABSTRACT FROM AUTHOR]

In this paper, the innovative fabrication process for electro-mechanical sensors, born from the smart combination of 3D-printing and wet-metallization and previously demonstrated in a $z$ -axis accelerometer, is employed to fabricate a fully 3D three-axis accelerometer. Thanks to the three-dimensionality of the printing process, a central symmetry along the three axes can be obtained by design, unlike in common 2D-like microfabrication processes. Electrostatic differential sensing is obtained through the metallization procedure and the subsequent mounting of fixed electrodes on an external frame of the mechanical structure. Experimental tests under accelerations show good agreement with theoretical predictions. With relatively small dimensions (features as low as $450~\mu \text{m}$), very high capacitive sensitivity (> 200 fF/g) and low theoretical thermo-mechanical noise, the proposed three-axis accelerometer represents a further step towards the development of an innovative fabrication process for high-performance, customizable, and low-cost electro-mechanical devices. [ABSTRACT FROM AUTHOR]

Glass (GFR) and carbon fiber-reinforced (CFR) dual-cure polymer composites fabricated by UV-assisted three-dimensional (UV-3D) printing are presented. The resin material combines an acrylic-based photocurable resin with a low temperature (140 oC) thermally-curable resin system based on bisphenol A diglycidyl ether as base component, an aliphatic anhydride (hexahydro-4-methylphthalic anhydride) as hardener and (2,4,6,-tris(dimethylaminomethyl)phenol) as catalyst. A thorough rheological characterization of these formulations allowed us to define their 3D printability window. UV-3D printed macrostructures were successfully demonstrated, giving a clear indication of their potential use in real-life structural applications. Differential scanning calorimetry and dynamic mechanical analysis highlighted the good thermal stability and mechanical properties of the printed parts. In addition, uniaxial tensile tests were used to assess the fiber reinforcing effect on the UV-3D printed objects. Finally, an initial study was conducted on the use of a sizing treatment on carbon fibers to improve the fiber/matrix interfacial adhesion, giving preliminary indications on the potential of this approach to improve the mechanical properties of the 3D printed CFR components. [ABSTRACT FROM AUTHOR]

In this work a sequential interpenetrating polymer network (IPN) obtained by co-formulation of a photocurable acrylic resin with a thermocurable epoxy resin is presented and proposed as matrix for the fabrication of carbon-fiber reinforced (CFR) composite structures by means of 3D-printing technology. This approach combines the advantages of the easy free-form fabrication typical of the 3D-printing technology with the purposely customized features of the newly developed IPN material. Photocalorimetric and dynamic-mechanical analyses were performed in order to investigate the photo- and thermal-crosslinking reactions and their effect on the development of the IPN system. The IPN resin was finally loaded with carbon fibers and successfully ultraviolet-assisted (UV)-3D printed, demonstrating the possibility of fabricating CFR composite materials in 3D with excellent mechanical properties. Being the first example of direct fabrication of IPN-based composites by 3D printing, this study clearly shows the great potential of this additive manufacturing technology for advanced industrial applications. [ABSTRACT FROM AUTHOR]

Significance: Colorectal cancer incidence has decreased largely due to detection and removal of polyps. Computer-aided diagnosis development may improve on polyp detection and discrimination. Aim: To advance detection and discrimination using currently available commercial colonoscopy systems, we developed a deep neural network (DNN) separating the color channels from images acquired under narrow-band imaging (NBI) and white-light endoscopy (WLE). Approach: Images of normal colon mucosa and polyps from colonoscopies were studied. Each color image was extracted based on the color channel: red/green/blue. A multilayer DNN was trained using one-channel, two-channel, and full-color images. The trained DNN was then tested for performance in detection of polyps. Results: The DNN performed better using full-colored NBI over WLE images in the detection of polyps. Furthermore, the DNN performed better using the two-channel red + green images when compared to full-color WLE images. Conclusions: The separation of color channels from full-color NBI and WLE images taken from commercially available colonoscopes may improve the ability of the DNN to detect and discriminate polyps. Further studies are needed to better determine the color channels and combination of channels to include and exclude in DNN development for clinical use. [ABSTRACT FROM AUTHOR]

In this work, a newly prepared cationic/free‐radical photopolymer, which consists of two epoxies and a tetrafunctional acrylate, is presented for the first time for a visible light stereolithography (SL), showing the advantages of both cationic and free‐radical resins. An onium salt, commonly used as a cationic UV initiator, and a photosensitizer make the blend suitable for a near‐visible (405 nm) SL. An increase in the polymerization rate and a drop in the induction period are observed for the newly prepared cationic/free‐radical blend, compared with either only cationic systems or free‐radical resins. This suggests that the combination of cationic and free‐radical polymerizations in a single resin has a positive synergistic effect. The addition of silica nanoparticles to the blend provides a reinforcing and toughening effect. Indeed, the resin loaded with silica shows a 31% increase in the elastic modulus, compared with the unfilled resin. Regarding the values of tensile strength and elongation at break, they, respectively, grow by 47 and 15%, when the nanocomposite resin is compared with the neat resin. A very low volumetric shrinkage of 0.7% and a remarkable printing quality of objects obtained with this new photopolymer will enable the 3D printing of microrobots, bioengineering microdevices, and sensors. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48333. [ABSTRACT FROM AUTHOR]