Design and Fabrication of a Band-Pass Filter With EBG Single-Ridge Waveguide Using Additive Manufacturing Techniques

A novel band-pass filter topology in waveguide technology is presented in this work. The proposed filter design is based on a periodic structure that uses modified sections of a single-ridge waveguide (SRW) as the unit cell to produce the desired frequency response. Two-step height profiles are included in the central part of the SRW, which provide useful parameters to yield a simple design method to achieve the required filtering characteristics. The suggested topology and design process are used to achieve band-pass filter responses with different fractional bandwidth and rejection characteristics. A 54% fractional bandwidth band-pass filter centered at 5.4 GHz is implemented using low cost 3-D additive manufacturing techniques, which allow fast prototyping and the fabrication of complex geometries. Experimental measurements are in agreement with the expected simulated response of the designed band-pass filter

Shape fidelity and sterility assessment of 3D printed polycaprolactone and hydroxyapatite scaffolds

AbstractPolycaprolactone (PCL) and hydroxyapatite (HA) composite are widely used in tissue engineering (TE). They are fit to being processed with three-dimensional (3D) printing technique to create scaffolds with verifiable porosity. The current challenge is to guarantee the reliability and reproducibility of 3D printed scaffolds and to create sterile scaffolds which can be used for in vitro cell cultures. In this context it is important for successful cell culture, to have a protocol in order to evaluate the sterility of the printed scaffolds. We proposed a systematic approach to sterilise 90%PCL-10%HA pellets using a 3D bioprinter before starting the printing process. We evaluated the printability of PCL-HA composite and the shape fidelity of scaffolds printed with and without sterilised pellets varying infill pattern, and the sterility of 3D printed scaffolds following the method established by the United States Pharmacopoeia. Finally, the thermal analyses supported by the Fourier Transform Infrared Spectroscopy were useful to verify the stability of the sterilisation process in the PCL solid state with and without HA. The results show that the use of the 3D printer, according to the proposed protocol, allows to obtain sterile 3D PCL-HA scaffolds suitable for TE applications such as bone or cartilage repair

Filament Path Optimization with Curvilinear Trajectories for Additive Manufacturing of Load-Bearing Components

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Quasar feedback in the early Universe: the case of SDSS J1148+5251

Galaxy-scale gas outflows triggered by active galactic nuclei have been proposed as a key physical process to regulate the co-evolution of nuclear black holes and their host galaxies. The recent detection of a massive gas outflow in one of the most distant quasar, SDSS J1148+5251 at z = 6.4, presented by Maiolino et al. (2012) strongly supports this idea and suggests that strong quasar feedback is already at work at very early times. In a previous work, Valiante et al. (2011), we have presented a hierarchical semi-analytical model, GAMETE/ QSOdust, for the formation and evolution of high-redshift quasars, and we have applied it to the quasar SDSS J1148+5251, with the aim of investigating the star formation history, the nature of the dominant stellar populations and the origin and properties of the large dust mass observed in the host galaxy. A robust prediction of the model is that the evolution of the nuclear black hole and of the host galaxy are tightly coupled by quasar feedback in the form of strong galaxy-scale winds. In the present letter, we show that the gas outflow rate predicted by GAMETE/QSOdust is in good agreement with the lower limit of 3500 Msun/yr inferred by the observations. According to the model, the observed outflow at z = 6.4 is dominated by quasar feedback, as the outflow rate has already considerably depleted the gas content of the host galaxy, leading to a down-turn in the star formation rate at z < 7 - 8. Hence, supernova explosions give a negligible contribution to the observed winds at z = 6.4.Comment: 5 pages, 4 figures, accepted for publication in MNRAS Letter

Enhanced Uptake and Phototoxicity of C60@albumin Hybrids by Folate Bioconjugation

Fullerenes are considered excellent photosensitizers, being highly suitable for photodynamic therapy (PDT). A lack of water solubility and low biocompatibility are, in many instances, still hampering the full exploitation of their potential in nanomedicine. Here, we used human serum albumin (HSA) to disperse fullerenes by binding up to five fullerene cages inside the hydrophobic cavities. Albumin was bioconjugated with folic acid to specifically address the folate receptors that are usually overexpressed in several solid tumors. Concurrently, tetramethylrhodamine isothiocyanate, TRITC, a tag for imaging, was conjugated to C-60@HSA in order to build an effective phototheranostic platform. The in vitro experiments demonstrated that: (i) HSA disperses C-60 molecules in a physiological environment, (ii) HSA, upon C-60 binding, maintains its biological identity and biocompatibility, (iii) the C-60@HSA complex shows a significant visible-light-induced production of reactive oxygen species, and (iv) folate bioconjugation improves both the internalization and the PDT-induced phototoxicity of the C-60@HSA complex in HeLa cells

Validation and Verification of High-Fidelity Simulations of Thoracic Stent-Graft Implantation

Thoracic Endovascular Aortic Repair (TEVAR) is the preferred treatment option for thoracic aortic pathologies and consists of inserting a self-expandable stent-graft into the pathological region to restore the lumen. Computational models play a significant role in procedural planning and must be reliable. For this reason, in this work, high-fidelity Finite Element (FE) simulations are developed to model thoracic stent-grafts. Experimental crimp/release tests are performed to calibrate stent-grafts material parameters. Stent pre-stress is included in the stent-graft model. A new methodology for replicating device insertion and deployment with explicit FE simulations is proposed. To validate this simulation, the stent-graft is experimentally released into a 3D rigid aortic phantom with physiological anatomy and inspected in a computed tomography (CT) scan at different time points during deployment with an ad-hoc set-up. A verification analysis of the adopted modeling features compared to the literature is performed. With the proposed methodology the error with respect to the CT is on average 0.92 +/- 0.64%, while it is higher when literature models are adopted (on average 4.77 +/- 1.83%). The presented FE tool is versatile and customizable for different commercial devices and applicable to patient-specific analyses

Assessment of different manufacturing techniques for the production of bioartificial scaffolds as soft organ transplant substitutes

Introduction: The problem of organs’ shortage for transplantation is widely known: different manufacturing techniques such as Solvent casting, Electrospinning and 3D Printing were considered to produce bioartificial scaffolds for tissue engineering purposes and possible transplantation substitutes. The advantages of manufacturing techniques’ combination to develop hybrid scaffolds with increased performing properties was also evaluated.Methods: Scaffolds were produced using poly-L-lactide-co-caprolactone (PLA-PCL) copolymer and characterized for their morphological, biological, and mechanical features.Results: Hybrid scaffolds showed the best properties in terms of viability (&gt;100%) and cell adhesion. Furthermore, their mechanical properties were found to be comparable with the reference values for soft tissues (range 1–10 MPa).Discussion: The created hybrid scaffolds pave the way for the future development of more complex systems capable of supporting, from a morphological, mechanical, and biological standpoint, the physiological needs of the tissues/organs to be transplanted

Teaching and learning human Anatomy in the University of Pavia: from models and clinical specimens to prosection on 3D models from our museum collection

Due to decline of resources and support for teaching human anatomy, in our Institute the use of cadaver dissection is not economically feasible. After a few years in which I was able to perform prosection on fixed organs belonging to the Institute collection, over the last years students learned topographical anatomy on commercial plastic models (bones, muscles, joints, trunks and brains). New perspectives recently occurred thanks to a collaboration with Prof. Auricchio’s group, which is involved in the strategic plan “3DPRINTING” (http://www. unipv.eu/site/home/area-stampa/articolo12952.html). First, we have segmented DICOM images of Computed Tomography (CT) to reconstruct 3D models of all the feet’s bones from a patient. Then, these 3D models have been post-processed to obtain suitable file for 3D printing. A 3DSYSTEMS ProJet 460 Plus, professional, full-color binder jetting printer (property of General Surgery2), has been used to create 3D models of feet’s bone by chalk powder binding. Medical students will use these models to test their own ability to recognize feet’s bones shape and to recompose them. Second, a plastic 3D anatomical model has been scanned by Artec Eva 3D Object Scanner to obtain a 3D virtual model of the physical one; this model has been modified to create a new modular model, printed with a process similar to one described above. Our Anatomy Institute is enriched by a Museum, established in the late eighteenth century by universally known anatomists (Rezia, Scarpa, Panizza, Zoja). This historical collection contains several sections (osteology, angiology, splanchnology, neurology and topographic anatomy). It is impossible to use these anatomical specimens of historical interest for prosection, but their life-size copies will constitute a cheap and effective method of learning. This strategy could not replace cadaver dissection experience but we hope that it could assist students in the comprehension of anatomical systems in a cost effective way within a systemic anatomy course. Besides, this method should optimize specimen’s choice and focalize student’s attention on peculiar, selected samples, preparing more appropriately medical students to their clinical practice

Qualitative Analysis of Traditional Italian Dishes : FTIR Approach

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