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1
Roulon, Stéphane, Ian Soulairol, Valérie Lavastre, Nicolas Payre, Maxime Cazes, Laurent Delbreilh e Jean Alié. "Production of Reproducible Filament Batches for the Fabrication of 3D Printed Oral Forms". Pharmaceutics 13, n. 4 (31 marzo 2021): 472. http://dx.doi.org/10.3390/pharmaceutics13040472.
Testo completoAbstract (sommario):
Patients need medications at a dosage suited to their physiological characteristics. Three-dimensional printing (3DP) technology by fused-filament fabrication (FFF) is a solution for manufacturing medication on demand. The aim of this work was to identify important parameters for the production of reproducible filament batches used by 3DP for oral formulations. Amiodarone hydrochloride, an antiarrhythmic and insoluble drug, was chosen as a model drug because of dosage adaptation need in children. Polyethylene oxide (PEO) filaments containing amiodarone hydrochloride were produced by hot-melt extrusion (HME). Different formulation storage conditions were investigated. For all formulations, the physical form of the drug following HME and fused-deposition modeling (FDM) 3D-printing processes were assessed using thermal analysis and X-ray powder diffraction (XRPD). Filament mechanical properties, linear mass density and surface roughness, were investigated by, respectively, 3-point bending, weighing, and scanning electron microscopy (SEM). Analysis results showed that the formulation storage condition before HME-modified filament linear mass density and, therefore, the oral forms masses from a batch to another. To obtain constant filament apparent density, it has been shown that a constant and reproducible drying condition is required to produce oral forms with constant mass.
2
Kennedy, Daniel T., e Robert A. Van Gorder. "Motion of open vortex-current filaments under the Biot–Savart model". Journal of Fluid Mechanics 836 (12 dicembre 2017): 532–59. http://dx.doi.org/10.1017/jfm.2017.826.
Testo completoAbstract (sommario):
Vortex-current filaments have been used to study phenomena such as coronal loops and solar flares as well as tokamaks, and recent experimental work has demonstrated dynamics akin to vortex-current filaments on a table-top plasma focus device. While MHD vortex dynamics and related applications to turbulence have attracted consideration in the literature due to a wide variety of applications, not much analytical progress has been made in this area, and the analysis of such vortex-current filament solutions under various geometries may motivate further experimental efforts. To this end, we consider the motion of open, isolated vortex-current filaments in the presence of magnetohydrodynamic (MHD) as well as the standard hydrodynamic effects. We begin with the vortex-current model of Yatsuyanagi, Hatori & Kato (J. Phys. Soc. Japan, vol. 65, 1996, pp. 745–759) giving the self-induced motion of a vortex-current filament. We give the ‘cutoff’ formulation of the Biot–Savart integrals used in this model, to avoid the singularity at the vortex core. We then study the motion of a variety of vortex-current filaments, including helical, planar and self-similar filament structures. In the case where MHD effects are weak relative to hydrodynamic effects, the filaments behave as expected from the pure hydrodynamic theory. However, when MHD effects are strong enough to dominate, then we observe structural changes to the filaments in all cases considered. The most common finding is reversal of vortex-current filament orientation for strong enough MHD effects. Kelvin waves along a vortex filament (as seen for helical and self-similar structures) will reverse their translational and rotational motion under strong MHD effects. Our findings support the view that vortex-current filaments can be studied in a manner similar to classical hydrodynamic vortex filaments, with the primary role of MHD effects being to change the filament motion, while preserving the overall geometric structure of such filaments.
3
Walker, B. J., K. Ishimoto, H. Gadêlha e E. A. Gaffney. "Filament mechanics in a half-space via regularised Stokeslet segments". Journal of Fluid Mechanics 879 (1 ottobre 2019): 808–33. http://dx.doi.org/10.1017/jfm.2019.723.
Testo completoAbstract (sommario):
We present a generalisation of efficient numerical frameworks for modelling fluid–filament interactions via the discretisation of a recently developed, non-local integral equation formulation to incorporate regularised Stokeslets with half-space boundary conditions, as motivated by the importance of confining geometries in many applications. We proceed to utilise this framework to examine the drag on slender inextensible filaments moving near a boundary, firstly with a relatively simple example, evaluating the accuracy of resistive force theories near boundaries using regularised Stokeslet segments. This highlights that resistive force theories do not accurately quantify filament dynamics in a range of circumstances, even with analytical corrections for the boundary. However, there is the notable and important exception of movement in a plane parallel to the boundary, where accuracy is maintained. In particular, this justifies the judicious use of resistive force theories in examining the mechanics of filaments and monoflagellate microswimmers with planar flagellar patterns moving parallel to boundaries. We proceed to apply the numerical framework developed here to consider how filament elastohydrodynamics can impact drag near a boundary, analysing in detail the complex responses of a passive cantilevered filament to an oscillatory flow. In particular, we document the emergence of an asymmetric periodic beating in passive filaments in particular parameter regimes, which are remarkably similar to the power and reverse strokes exhibited by motile$9+2$cilia. Furthermore, these changes in the morphology of the filament beating, arising from the fluid–structure interactions, also induce a significant increase in the hydrodynamic drag of the filament.
4
Moreau, Clément, Laetitia Giraldi e Hermes Gadêlha. "The asymptotic coarse-graining formulation of slender-rods, bio-filaments and flagella". Journal of The Royal Society Interface 15, n. 144 (luglio 2018): 20180235. http://dx.doi.org/10.1098/rsif.2018.0235.
Testo completoAbstract (sommario):
The inertialess fluid–structure interactions of active and passive inextensible filaments and slender-rods are ubiquitous in nature, from the dynamics of semi-flexible polymers and cytoskeletal filaments to cellular mechanics and flagella. The coupling between the geometry of deformation and the physical interaction governing the dynamics of bio-filaments is complex. Governing equations negotiate elastohydrodynamical interactions with non-holonomic constraints arising from the filament inextensibility. Such elastohydrodynamic systems are structurally convoluted, prone to numerical errors, thus requiring penalization methods and high-order spatio-temporal propagators. The asymptotic coarse-graining formulation presented here exploits the momentum balance in the asymptotic limit of small rod-like elements which are integrated semi-analytically. This greatly simplifies the elastohydrodynamic interactions and overcomes previous numerical instability. The resulting matricial system is straightforward and intuitive to implement, and allows for a fast and efficient computation, more than a hundred times faster than previous schemes. Only basic knowledge of systems of linear equations is required, and implementation achieved with any solver of choice. Generalizations for complex interaction of multiple rods, Brownian polymer dynamics, active filaments and non-local hydrodynamics are also straightforward. We demonstrate these in four examples commonly found in biological systems, including the dynamics of filaments and flagella. Three of these systems are novel in the literature. We additionally provide a Matlab code that can be used as a basis for further generalizations.
5
Regnier, J., C. Cloarec, A. Cayla, C. Campagne e E. Devaux. "Multifilaments based on partially miscible polymers blend filled with carbon nanotubes". IOP Conference Series: Materials Science and Engineering 1266, n. 1 (1 gennaio 2023): 012020. http://dx.doi.org/10.1088/1757-899x/1266/1/012020.
Testo completoAbstract (sommario):
Abstract Many textile fields, such as industrial structures or clothing, use the electrical conductivity variation of yarns to detect fluid leakage. Such yarns can be developed by melt spinning conductive polymer composites (CPC). CPC filaments are composed of a polymer’s matrix which is blended with sufficient quantity of electrically conductive fillers to make the filament conductive. To combine properties or improve the compounds preparation, more and more studies are investigating different polymers blends. In this study, CPC monofilaments and multifilaments are developed and characterized to observe the formulation influence on spinnability and the implementation process on the water detection. Two principles of water detection are studied on the CPC which is composed of a blend of partially miscible polymers (polyethylene terephthalate (PET)/polybutylene terephthalate (PBT)) filled with carbon nanotubes (CNT). The principle of absorption is based on the electrical conductivity variation of the filament in contact with water. For the short circuit principle, the presence of the liquid is detected when the water creates a conductive path between two filaments in parallel.
6
Varan, Cem, Davut Aksüt, Murat Şen e Erem Bilensoy. "Design and Characterization of Carboplatin and Paclitaxel Loaded PCL Filaments for 3D Printed Controlled Release Intrauterine Implants". Pharmaceutics 15, n. 4 (5 aprile 2023): 1154. http://dx.doi.org/10.3390/pharmaceutics15041154.
Testo completoAbstract (sommario):
Uterine cancer is the fourth most common cancer in women. Despite various chemotherapy approaches, the desired effect has not yet been achieved. The main reason is each patient responds differently to standard treatment protocols. The production of personalized drugs and/or drug-loaded implants is not possible in today’s pharmaceutical industry; 3D printers allow for the rapid and flexible preparation of personalized drug-loaded implants. However, the key point is the preparation of drug-loaded working material such as filament for 3D printers. In this study, two different anticancer (paclitaxel, carboplatin) drug-loaded PCL filaments with a 1.75 mm diameter were prepared with a hot-melt extruder. To optimize the filament for a 3D printer, different PCL Mn, cyclodextrins and different formulation parameters were tried, and a series of characterization studies of filaments were conducted. The encapsulation efficiency, drug release profile and in vitro cell culture studies have shown that 85% of loaded drugs retain their effectiveness, provide a controlled release for 10 days and cause a decrease in cell viability of over 60%. In conclusion, it is possible to prepare optimum dual anticancer drug-loaded filaments for FDM 3D printers. Drug-eluting personalized intra-uterine devices can be designed for the treatment of uterine cancer by using these filaments.
7
Padilla, Marcel, Oliver Gross, Felix Knöppel, Albert Chern, Ulrich Pinkall e Peter Schröder. "Filament based plasma". ACM Transactions on Graphics 41, n. 4 (luglio 2022): 1–14. http://dx.doi.org/10.1145/3528223.3530102.
Testo completoAbstract (sommario):
Simulation of stellar atmospheres, such as that of our own sun, is a common task in CGI for scientific visualization, movies and games. A fibrous volumetric texture is a visually dominant feature of the solar corona---the plasma that extends from the solar surface into space. These coronal fibers can be modeled as magnetic filaments whose shape is governed by the magnetohydrostatic equation. The magnetic filaments provide a Lagrangian curve representation and their initial configuration can be prescribed by an artist or generated from magnetic flux given as a scalar texture on the sun's surface. Subsequently, the shape of the filaments is determined based on a variational formulation. The output is a visual rendering of the whole sun. We demonstrate the fidelity of our method by comparing the resulting renderings with actual images of our sun's corona.
8
Van Gorder, Robert A. "Helical vortex filament motion under the non-local Biot–Savart model". Journal of Fluid Mechanics 762 (3 dicembre 2014): 141–55. http://dx.doi.org/10.1017/jfm.2014.639.
Testo completoAbstract (sommario):
AbstractThe thin helical vortex filament is one of the fundamental exact solutions possible under the local induction approximation (LIA). The LIA is itself an approximation to the non-local Biot–Savart dynamics governing the self-induced motion of a vortex filament, and helical filaments have also been considered for the Biot–Savart dynamics, under a variety of configurations and assumptions. We study the motion of such a helical filament in the Cartesian reference frame by determining the curve defining this filament mathematically from the Biot–Savart model. In order to do so, we consider a matched approximation to the Biot–Savart dynamics, with local effects approximated by the LIA in order to avoid the logarithmic singularity inherent in the Biot–Savart formulation. This, in turn, allows us to determine the rotational and translational velocity of the filament in terms of a local contribution (which is exactly that which is found under the LIA) and a non-local contribution, each of which depends on the wavenumber, $k$, and the helix diameter, $A$. Performing our calculations in such a way, we can easily compare our results to those of the LIA. For small $k$, the transverse velocity scales as $k^{2}$, while for large $k$, the transverse velocity scales as $k$. On the other hand, the rotational velocity attains a maximum value at some finite $k$, which corresponds to the wavenumber giving the maximal torsion.
9
Prasad, Elke, John Robertson e Gavin W. Halbert. "An Additive Manufacturing MicroFactory: Overcoming Brittle Material Failure and Improving Product Performance through Tablet Micro-Structure Control for an Immediate Release Dose Form". Polymers 16, n. 18 (11 settembre 2024): 2566. http://dx.doi.org/10.3390/polym16182566.
Testo completoAbstract (sommario):
Additive manufacturing of pharmaceutical formulations offers advanced micro-structure control of oral solid dose (OSD) forms targeting not only customised dosing of an active pharmaceutical ingredient (API) but also custom-made drug release profiles. Traditionally, material extrusion 3D printing manufacturing was performed in a two-step manufacturing process via an intermediate feedstock filament. This process was often limited in the material space due to unsuitable (brittle) material properties, which required additional time to develop complex formulations to overcome. The objective of this study was to develop an additive manufacturing MicroFactory process to produce an immediate release (IR) OSD form containing 250 mg of mefenamic acid (MFA) with consistent drug release. In this study, we present a single-step additive manufacturing process employing a novel, filament-free melt extrusion 3D printer, the MicroFactory, to successfully print a previously ‘non-printable’ brittle Soluplus®-based formulation of MFA, resulting in targeted IR dissolution profiles. The physico-chemical properties of 3D printed MFA-Soluplus®-D-sorbitol formulation was characterised by thermal analysis, Fourier Transform Infrared spectroscopy (FTIR), and X-ray Diffraction Powder (XRPD) analysis, confirming the crystalline state of mefenamic acid as polymorphic form I. Oscillatory temperature and frequency rheology sweeps were related to the processability of the formulation in the MicroFactory. 3D printed, micro-structure controlled, OSDs showed good uniformity of mass and content and exhibited an IR profile with good consistency. Fitting a mathematical model to the dissolution data correlated rate parameters and release exponents with tablet porosity. This study illustrates how additive manufacturing via melt extrusion using this MicroFactory not only streamlines the manufacturing process (one-step vs. two-step) but also enables the processing of (brittle) pharmaceutical immediate-release polymers/polymer formulations, improving and facilitating targeted in vitro drug dissolution profiles.
10
Shia, C. Y., R. J. Stango e S. M. Heinrich. "Analysis of Contact Mechanics for a Circular Filamentary Brush/Workpart System". Journal of Manufacturing Science and Engineering 120, n. 4 (1 novembre 1998): 715–21. http://dx.doi.org/10.1115/1.2830211.
Testo completoAbstract (sommario):
This paper addresses the contact problem associated with the filament/workpart interaction that arises during brushing processes. A discretized model of a filament within the brushing tool is developed by employing Lagrange’s equations in conjunction with special constraint equations that are appropriate for the impact and impending large displacement of a flexible fiber whose tip traverses a flat, rigid surface. This formulation leads to the identification of five nondimensional parameters which fully characterize the filament/workpart contact problem. A damping mechanism is also included which can be used for modeling complex filament interactions that arise during the actual brushing operation. Special consideration is given to examining the initial filament/workpart impact and the subsequent forces that are generated along the contact region. Initial velocity of the filament is determined by employing an inelastic impact mechanics analysis. Time-varying transient response of the filament is then obtained by employing a predictor-corrector technique in conjunction with a finite difference method. Overall brush force is computed by a superposition of filament contact forces exerted onto the workpart surface. Numerical results are reported and compared with experimentally obtained data for an actual brush/workpart system.
11
Wang, Yongxing, Shujia Li, Xunxun Ma, Dayu Zhang, Pei Feng e Shengze Wang. "An analytical approach of filament bundle swinging dynamics, Part I: Modeling filament bundle by ANCF". Textile Research Journal 89, n. 21-22 (2 aprile 2019): 4607–19. http://dx.doi.org/10.1177/0040517519836940.
Testo completoAbstract (sommario):
A filament bundle is a kind of filament assembly with less twist or nontwist. It is a viscoelastic body and has a large aspect ratio. Its large deformation during motion over a wide range is a universal phenomenon in many textile processes. The dynamic viscoelasticity of the filament bundle, gravity, and air resistance are three important factors affecting the filament bundle's dynamic behavior. Taking account of these factors, a filament bundle dynamics analysis method is proposed in a series of three papers. This paper, the first in the series, presents an approach to model the dynamics of the flexible filament bundle with viscoelasticity and to analyze its dynamic behavior under the action of gravity and air resistance. The filament bundle element (FBE) is established based on absolute nodal coordinate formulation (ANCF), in which slope vectors and global coordinates are applied. The approach presented in this paper is well suited for the analysis of large deformation motions of filament bundles. As an example, a dynamic model was established to predict the filament bundle's trace during its swinging through large displacements under the action of gravity and air resistance, taking into account the filament bundle viscosity. The nonlinear differential equations of the filament bundle system were solved using MATLAB. Furthermore, the swing traces of the filament bundle in a closed Plexiglas box with different vacuum degrees were recorded using a high-speed camera to prove the validity of the established filament bundle model based on ANCF.
12
Roonthong, Buncha, Sorawit Damdenngam, Nutthanon Intarasuwan, Nismar Parneam, Patpimol Suwankan e Siriorn Isarankura Na Ayutthaya. "Effect of h-NS Content on the Viscosity, Morphology, Gelation, and Mechanical Properties of the Modified-rPET from Bottle Waste". Materials Science Forum 1129 (30 ottobre 2024): 3–9. http://dx.doi.org/10.4028/p-8fiwdt.
Testo completoAbstract (sommario):
This research developed the modified-recycled poly (ethylene terephthalate) (modified-rPET) filament by decreasing the crosslinked-gel content inside the filament, by adding various contents of hydrophobic nanosilica (h-NS). This research also studies the viscosity, morphology, h-NS dispersion, and mechanical properties of the modified-rPET/h-NS, by using a rotational rheometer, a scanning electron microscope, a micro-XRF spectrometer, and a universal testing machine, respectively. rPET flakes were dried to deplete the moisture. Then, they were mixed with additives and h-NS at 0, 1, 2, 3, 4, and 5 pph, and were extruded to be compound using twin screw extruder. The modified-rPET/h-NS extrudates were investigated into two parts. Firstly, was observed on the process-ability, morphology, and gel content along the filament. Consequently, the viscosity, mechanical properties, and h-NS dispersion were investigated. The results showed that the best formulation that is easy to process and has the lowest gel content along the filament, was NS1. Other results, shear-thinning rheology behaviors were observed for all formulations. The mechanical properties, including ultimate tensile strength and elongation at break decreased, as the h-NS content increased. At higher content of h-NS (NS4 and NS5), the gel content increased significantly, therefore the h-NS agglomeration occurred, which was different from crosslinked gels.
13
Azami, I., P. Kurniasih, S. ., A. Amantha, N. Habiiburrahman e N. H. Sari. "Filamen printer 3D berbasis limbah PET (polyethylene terephthalate) dan kitosan cangkang udang". Dinamika Teknik Mesin 14, n. 1 (1 aprile 2024): 82. http://dx.doi.org/10.29303/dtm.v14i1.759.
Testo completoAbstract (sommario):
One alternative for processing PET (polyethylene terephthalate) plastic waste is to convert it into a basic material for making 3D printer filaments with the addition of shrimp shell chitosan. The addition of shrimp shell chitosan to the filament can increase its mechanical strength. The aim of this research is to determine the best formulation and effectiveness of the combination of PET plastic with chitosan as 3D printer filament on the mechanical properties and microstructure of the surface. Making 3D printer filament from a combination of PET and shrimp shell chitosan using a double screw extruder with varying ratios between PET and shrimp shell chitosan (99 : 1, 97.5 : 2.5 and 95 : 5) with temperature variations at 175° C (Hopper Zone ), 195°C, 225°C, 245°C (Die zone) using a screw rotation speed of 50 rpm, with the testing process including a tensile test, to determine the mechanical properties of the material by analysis using the SEM (Scanning Electron Microscope) test ) to identify the surface morphology and size of the filament material. The test results for composition 99:1 (sample 1) had the lowest tensile strength value of 35.79 MPa, breaking 0.10 mm with an elongation value of 0.32%. Composition 97.5:2.5 (sample 2) with a tensile strength value of 96.20 Mpa, longest breaking length of 0.13 mm and highest elongation value of 0.42%. Composition 95:5 (sample 3) only has the highest tensile value of 98.95 MPa, with a breaking length of 0.06 mm and the lowest elongation of 0.18%.
14
Rossetti, Valentina, Manuela Filippini, Miroslav Svercel, A. D. Barbour e Homayoun C. Bagheri. "Emergent multicellular life cycles in filamentous bacteria owing to density-dependent population dynamics". Journal of The Royal Society Interface 8, n. 65 (18 maggio 2011): 1772–84. http://dx.doi.org/10.1098/rsif.2011.0102.
Testo completoAbstract (sommario):
Filamentous bacteria are the oldest and simplest known multicellular life forms. By using computer simulations and experiments that address cell division in a filamentous context, we investigate some of the ecological factors that can lead to the emergence of a multicellular life cycle in filamentous life forms. The model predicts that if cell division and death rates are dependent on the density of cells in a population, a predictable cycle between short and long filament lengths is produced. During exponential growth, there will be a predominance of multicellular filaments, while at carrying capacity, the population converges to a predominance of short filaments and single cells. Model predictions are experimentally tested and confirmed in cultures of heterotrophic and phototrophic bacterial species. Furthermore, by developing a formulation of generation time in bacterial populations, it is shown that changes in generation time can alter length distributions. The theory predicts that given the same population growth curve and fitness, species with longer generation times have longer filaments during comparable population growth phases. Characterization of the environmental dependence of morphological properties such as length, and the number of cells per filament, helps in understanding the pre-existing conditions for the evolution of developmental cycles in simple multicellular organisms. Moreover, the theoretical prediction that strains with the same fitness can exhibit different lengths at comparable growth phases has important implications. It demonstrates that differences in fitness attributed to morphology are not the sole explanation for the evolution of life cycles dominated by multicellularity.
15
Adali, Sarp. "Variational Principles for Buckling of Microtubules Modeled as Nonlocal Orthotropic Shells". Computational and Mathematical Methods in Medicine 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/591532.
Testo completoAbstract (sommario):
A variational principle for microtubules subject to a buckling load is derived by semi-inverse method. The microtubule is modeled as an orthotropic shell with the constitutive equations based on nonlocal elastic theory and the effect of filament network taken into account as an elastic surrounding. Microtubules can carry large compressive forces by virtue of the mechanical coupling between the microtubules and the surrounding elastic filament network. The equations governing the buckling of the microtubule are given by a system of three partial differential equations. The problem studied in the present work involves the derivation of the variational formulation for microtubule buckling. The Rayleigh quotient for the buckling load as well as the natural and geometric boundary conditions of the problem is obtained from this variational formulation. It is observed that the boundary conditions are coupled as a result of nonlocal formulation. It is noted that the analytic solution of the buckling problem for microtubules is usually a difficult task. The variational formulation of the problem provides the basis for a number of approximate and numerical methods of solutions and furthermore variational principles can provide physical insight into the problem.
16
Schwartz, Johanna J., Joshua Hamel, Thomas Ekstrom, Leticia Ndagang e Andrew J. Boydston. "Not all PLA filaments are created equal: an experimental investigation". Rapid Prototyping Journal 26, n. 7 (27 giugno 2020): 1263–76. http://dx.doi.org/10.1108/rpj-06-2019-0179.
Testo completoAbstract (sommario):
Purpose Additive manufacturing (AM) methods such as material extrusion (ME) are becoming widely used by engineers, designers and hobbyists alike for a wide variety of applications. Successfully manufacturing objects using ME three-dimensional printers can often require numerous iterations to attain predictable performance because the exact mechanical behavior of parts fabricated via additive processes are difficult to predict. One of that factors that contributes to this difficulty is the wide variety of ME feed stock materials currently available in the marketplace. These build materials are often sold based on their base polymer material such as acrylonitrile butadiene styrene or polylactic acid (PLA), but are produced by numerous different commercial suppliers in a wide variety of colors using typically undisclosed additive feed stocks and base polymer formulations. This paper aims to present the results from an experimental study concerned with quantifying how these sources of polymer variability can affect the mechanical behavior of three-dimensional printed objects. Specifically, the set of experiments conducted in this study focused on following: several different colors of PLA filament from a single commercial supplier to explore the effect of color additives and three filaments of the same color but produced by three different suppliers to account for potential variations in polymer formulation. Design/methodology/approach A set of five common mechanical and material characterization tests were performed on 11 commercially available PLA filaments in an effort to gain insight into the variations in mechanical response that stem from variances in filament manufacturer, feed stock polymer, additives and processing. Three black PLA filaments were purchased from three different commercial suppliers to consider the variations introduced by use of different feed stock polymers and filament processing by different manufacturers. An additional eight PLA filaments in varying colors were purchased from one of the three suppliers to focus on how color additives lead to property variations. Some tests were performed on unprocessed filament samples, while others were performed on objects three-dimensional printed from the various filaments. This study looked specifically at four mechanical properties (Young’s modulus, storage modulus, yield strength and toughness) as a function of numerous material properties (e.g. additive loading, molecular weight, molecular weight dispersity, enthalpy of melting and crystallinity). Findings For the 11 filaments tested the following mean values and standard deviations were observed for the material properties considered: pa = 1.3 ± 0.9% (percent additives), Mw = 98.6 ± 16.4 kDa (molecular weight), Ð = 1.33 ± 0.1 (molecular weight dispersity), Hm = 37.4 ± 7.2 J/g (enthalpy of melting) and = 19.6 ± 2.1% (crystallinity). The corresponding mean values and standard deviations for the resulting mechanical behaviors were: E = 2,790 ± 145 MPa (Young’s modulus), E’ = 1,050 ± 125 MPa (storage modulus), Sy = 49.6 ± 4.93 MPa (yield strength) and Ut = 1.87 ± 0.354 MJ/m^3 (toughness). These variations were observed in filaments that were all manufactured from the same base polymer (e.g. PLA) and are only different in terms of the additives used by the manufacturers to produce different colors or different three-dimensional printing performance. Unfortunately, while the observed variations were significant, no definitive strong correlations were found between these observed variations in the mechanical behavior of the filaments studied and the considered material properties. Research limitations/implications These variations in mechanical behavior and material properties could not be ascribed to any specific factor, but rather show that the mechanical of three-dimensional printed parts are potentially affected by variations in base polymer properties, additive usage and filament processing choices in complex ways that can be difficult to predict. Practical implications These results emphasize the need to take processing and thereby even filament color, into account when using ME printers, they emphasize the need for designers to use AM with caution when the mechanical behavior of a printed part is critical and they highlight the need for continued research in this important area. While all filaments used were marked as PLA, the feedstock materials, additives and processing conditions created significant differences in the mechanical behavior of the printed objects evaluated, but these differences could not be accurately and reliably predicted as function of the observed material properties that were the focus of this study. Originality/value The testing methods used in the study can be used by engineers and creators alike to better analyze the material properties of their filament printed objects, to increase success in print and mechanical design. Furthermore, the results clearly show that as AM continues to evolve and grow as a manufacturing method, standardization of feedstock processing conditions and additives would enable more reliable and repeatable printed objects and would better assist designers in effectively implementing AM methods.
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Hartzke, David, Axel Pössl, Peggy Schlupp e Frank E. Runkel. "Evaluation of Hydroxyethyl Cellulose Grades as the Main Matrix Former to Produce 3D-Printed Controlled-Release Dosage Forms". Pharmaceutics 14, n. 10 (1 ottobre 2022): 2103. http://dx.doi.org/10.3390/pharmaceutics14102103.
Testo completoAbstract (sommario):
Diclofenac sodium tablets were successfully prepared via hot-melt extrusion (HME) and fused deposition modeling (FDM), using different molecular-weight (Mw) grades of hydroxyethyl cellulose (HEC) as the main excipient. Hydroxypropyl cellulose (HPC) was added to facilitate HME and to produce drug-loaded, uniform filaments. The effect of the HEC grades (90–1000 kDa) on the processability of HME and FDM was assessed. Mechanical properties of the filaments were evaluated using the three-point bend (3PB) test. Breaking stress and distance were set in relation to the filament feedability to identify printer-specific thresholds that enable proper feeding. The study demonstrated that despite the HEC grade used, all formulations were at least printable. However, only the HEC L formulation was feedable, showing the highest breaking stress (29.40 ± 1.52 MPa) and distance (1.54 ± 0.08 mm). Tablet drug release showed that the release was Mw dependent up to a certain HEC Mw limit (720 kDa). Overall, the release was driven by anomalous transport due to drug diffusion and polymer erosion. The results indicate that despite being underused in FDM, HEC is a suitable main excipient for 3D-printed dosage forms. More research on underutilized polymers in FDM should be encouraged to increase the limited availability.
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Stango, R. J., e Chih-Yuan Shia. "Analysis of Filament Deformation for a Freely Rotating Cup Brush". Journal of Manufacturing Science and Engineering 119, n. 3 (1 agosto 1997): 298–306. http://dx.doi.org/10.1115/1.2831107.
Testo completoAbstract (sommario):
In this paper, a mechanics formulation is outlined and used for evaluating the steady-state, large deflection of a slender member subjected to displacement-dependent centrifugal load. The problem is examined within the context of rotating filamentary cup brushes that are used in surface finishing operations. Several parameters which are closely related to the machining performance and service life of cup brushes are identified and reported, including filament tip spatial distribution and orientation, filament stress, and the steady-state configuration of the working surface of the cup brush during free rotation. Numerical results indicate that filament inertia forces can lead to significant fiber displacement and stress and thus, must be included as an integral part of the design of rotary cup brushes.
19
Algellay, Marwan, Matthew Roberts, Lucy Bosworth, Satyajit D. Sarker, Amos A. Fatokun e Touraj Ehtezazi. "The Use of Micro-Ribbons and Micro-Fibres in the Formulation of 3D Printed Fast Dissolving Oral Films". Pharmaceuticals 16, n. 1 (5 gennaio 2023): 79. http://dx.doi.org/10.3390/ph16010079.
Testo completoAbstract (sommario):
Three-dimensional printing (3DP) allows production of novel fast dissolving oral films (FDFs). However, mechanical properties of the films may not be desirable when certain excipients are used. This work investigated whether adding chitosan micro-ribbons or cellulose microfibres will achieve desired FDFs by fused deposition modelling 3DP. Filaments containing polyvinyl alcohol (PVA) and paracetamol as model drug were manufactured at 170 °C. At 130 °C, filaments containing polyvinylpyrrolidone (PVP) and paracetamol were also created. FDFs were printed with plain or mesh patterns at temperatures of 200 °C (PVA) or 180 °C (PVP). Both chitosan micro-ribbons and cellulose micro-fibres improved filament mechanical properties at 1% w/w concentration in terms of flexibility and stiffness. The filaments were not suitable for printing at higher concentrations of chitosan micro-ribbons and cellulose micro-fibres. Furthermore, mesh FDFs containing only 1% chitosan micro-ribbons disintegrated in distilled water within 40.33 ± 4.64 s, while mesh FDFs containing only 7% croscarmellose disintegrated in 55.33 ± 2.86 s, and croscarmellose containing films showed signs of excipient scorching for PVA polymer. Cellulose micro-fibres delayed disintegration of PVA mesh films to 108.66 ± 3.68 s at 1% w/w. In conclusion, only chitosan micro-ribbons created a network of hydrophilic channels within the films, which allowed faster disintegration time at considerably lower concentrations.
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Ftoutou, Ezzeddine, Lamis Allegue, Haykel Marouani, Tarek Hassine, Yasser Fouad e Hatem Mrad. "Modeling of Effect of Infill Density Percentage on Rotating Bending Fatigue Behavior of Additive-Manufactured PLA Polymers". Materials 17, n. 2 (19 gennaio 2024): 471. http://dx.doi.org/10.3390/ma17020471.
Testo completoAbstract (sommario):
Nowadays, 3D PLA-printed parts are widely used in many applications, essentially using the fused filament fabrication technique. While the influence of printing parameters on quasi-static mechanical characterization has been extensively considered within the literature, there are limited accounts of this effect on fatigue performance. The two main aims of this research are first to investigate the effects of the infill density percentage on the fatigue life of dog-bone samples under rotating bending cycling loads, and second to model the fatigue life using Wöhler and Basquin models. The experiments exhibit a high variability of results, especially for low cyclic loads. The S–N curves show that the number of cycles at failure increases with the increase in the infill density percentage and decreases with the increase in loads. Investigations allow the formulation of each constant model as a function of the infill density percentage. The new fatigue model formulations exhibit good agreement with the experimental data. As an outcome of this study, the fatigue model for 3D-printed parts may be expressed as a function of the infill density percentage using fewer tests in the future and for other polymers used in fused filament fabrication.
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Sohif, Hajar Naemah, Wan Muhammad Zulfadli Wan Sulaiman, Hanisah Manshor, Ahmad Zahirani Ahmad Azhar e Nor Aiman Sukindar. "Experimental Investigation on Surface Roughness, Hardness and Tensile Strength of Rice Husk (RH) as a Filler for Formulation of Polethylene-Terephthalate Glycol (PETG) 3D Filament Title of Manuscript". Semarak International Journal of Material Research 2, n. 1 (28 febbraio 2025): 1–11. https://doi.org/10.37934/sijmr.2.1.111.
Testo completoAbstract (sommario):
Three-dimensional (3D) printing is one of the most widely used additive manufacturing techniques which is able to produce physical objects from geometrical illustrations using the applicable material. Polyethylene Terephthalate Glycol (PETG) is an additively manufacturable polymer material which is gaining attention for its excellent mechanical and chemical properties. However, it has mechanical limitations that restrict its broader use in 3D printing. Thus, reinforcing with natural fibers like rice husk (RH), an agricultural byproduct, show potentials in improving polymer composites. Nonetheless, their potential when blended with PETG for 3D printing applications are insufficiently explored, emphasizing the need for a systematic investigation. Henceforth, the present work seeks to formulate a 3D printing filament using PETG with RH powder that aims to enhance the mechanical properties of 3D-printed filament. This work also finds the mechanical interactions between varying ratios of PETG and RH to determine optimal composition for enhanced properties focusing on surface roughness, hardness and tensile strength. The PETG/RH filaments were produced from crushed raw RH and pellet form PETG. The varying ratios of RH at 0%, 2%, 6%, and 10% were blended with PETG into an extruder. The roughness of the surface was evaluated by direct imaging. The smoother filament was observed when loading up to 6 wt.% RH. In hardness and tensile strength test, the hardness and strength increased with loading up to 6 wt.% RH. This paper presents the results of optimal ratios of PETG/RH at 6 wt.%, as it improves surface roughness, hardness and tensile strength of PETG. This study adopted the same stance and claimed that the fiber’s tensile strength and hardness increased along with its weight until an optimal level. However, further increase in the sample leads to a stronger fiber-fiber bond which it weakens the interfacial bond of fiber-matrix. Weak interfacial bond of fiber-matrix resulting in inefficient load transfer, hence decrease the sample’s mechanical properties.
22
Kasmi, Samir, Julien Cayuela, Bertrand De Backer, Eric Labbé e Sébastien Alix. "Modified Polylactic Acid with Improved Impact Resistance in the Presence of a Thermoplastic Elastomer and the Influence of Fused Filament Fabrication on Its Physical Properties". Journal of Composites Science 5, n. 9 (2 settembre 2021): 232. http://dx.doi.org/10.3390/jcs5090232.
Testo completoAbstract (sommario):
The standard polylactic acid (PLA), as a biodegradable thermoplastic polymer, is commonly used in various industrial sectors, food, and medical fields. Unfortunately, it is characterized by a low elongation at break and low impact energy. In this study, a thermoplastic copolyester elastomer (TPCE) was added at different weight ratios to improve the impact resistance of PLA. DSC analysis revealed that the two polymers were immiscible. A good balance of impact resistance and rigidity was reached using the formulation that was composed of 80% PLA and 20% TPCE, with an elongation at break of 155% compared to 4% for neat PLA. This new formulation was selected to be tested in a fused filament fabrication process. The influence of the nozzle and bed temperatures as printing parameters on the mechanical and thermal properties was explored. Better impact resistance was observed with the increase in the two thermal printing parameters. The crystallinity degree was not influenced by the variation in the nozzle temperature. However, it was increased at higher bed temperatures. Tomographic observations showed an anisotropic distribution of the porosity, where it was mostly present between the adjacent printed filaments and it was reduced with the increase in the nozzle and bed temperatures.
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Reddy Dumpa, Nagi, Suresh Bandari e Michael A. Repka. "Novel Gastroretentive Floating Pulsatile Drug Delivery System Produced via Hot-Melt Extrusion and Fused Deposition Modeling 3D Printing". Pharmaceutics 12, n. 1 (8 gennaio 2020): 52. http://dx.doi.org/10.3390/pharmaceutics12010052.
Testo completoAbstract (sommario):
This study was performed to develop novel core-shell gastroretentive floating pulsatile drug delivery systems using a hot-melt extrusion-paired fused deposition modeling (FDM) 3D printing and direct compression method. Hydroxypropyl cellulose (HPC) and ethyl cellulose (EC)-based filaments were fabricated using hot-melt extrusion technology and were utilized as feedstock material for printing shells in FDM 3D printing. The directly compressed theophylline tablet was used as the core. The tablet shell to form pulsatile floating dosage forms with different geometries (shell thickness: 0.8, 1.2, 1.6, and 2.0 mm; wall thickness: 0, 0.8, and 1.6 mm; and % infill density: 50, 75, and 100) were designed, printed, and evaluated. All core-shell tablets floated without any lag time and exhibited good floating behavior throughout the dissolution study. The lag time for the pulsatile release of the drug was 30 min to 6 h. The proportion of ethyl cellulose in the filament composition had a significant (p < 0.05) effect on the lag time. The formulation (2 mm shell thickness, 1.6 mm wall thickness, 100% infill density, 0.5% EC) with the desired lag time of 6 h was selected as an optimized formulation. Thus, FDM 3D printing is a potential technique for the development of complex customized drug delivery systems for personalized pharmacotherapy.
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Ophir, Z., A. Buchman, F. Flashner, I. Liran, H. Simons e H. Dodiuk. "Modified epoxy formulation for improving the fracture resistance of filament wound pressure vessels". Journal of Adhesion Science and Technology 9, n. 2 (gennaio 1995): 159–75. http://dx.doi.org/10.1163/156856195x01102.
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Sáiz, Luciana M., Antonela B. Orofino, Exequiel S. Rodríguez, Ileana A. Zucchi e Roberto J. J. Williams. "Epoxy formulation including an acrylic triblock copolymer adapted for use in filament winding". Polymer Engineering & Science 56, n. 10 (1 giugno 2016): 1153–59. http://dx.doi.org/10.1002/pen.24348.
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Caltagirone, Jean-Paul. "The Role of Inertia in the Onset of Turbulence in a Vortex Filament". Fluids 8, n. 1 (2 gennaio 2023): 16. http://dx.doi.org/10.3390/fluids8010016.
Testo completoAbstract (sommario):
The decay of the kinetic energy of a turbulent flow with time is not necessarily monotonic. This is revealed by simulations performed in the framework of discrete mechanics, where the kinetic energy can be transformed into pressure energy or vice versa; this persistent phenomenon is also observed for inviscid fluids. Different types of viscous vortex filaments generated by initial velocity conditions show that vortex stretching phenomena precede an abrupt onset of vortex bursting in high-shear regions. In all cases, the kinetic energy starts to grow by borrowing energy from the pressure before the transfer phase to the small turbulent structures. The result observed on the vortex filament is also found for the Taylor–Green vortex, which significantly differs from the previous results on this same case simulated from the Navier–Stokes equations. This disagreement is attributed to the physical model used, that of discrete mechanics, where the formulation is based on the conservation of acceleration. The reasons for this divergence are analyzed in depth; however, a spectral analysis allows finding the established laws on the decay of kinetic energy as a function of the wave number.
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Rubiano Buitrago, Julián David, Andrés Fernando Gil Plazas, Luis Alejandro Boyacá Mendivelso e Liz Karen Herrera Quintero. "Fused Filament Fabrication of WC-10Co Hardmetals: A Study on Binder Formulations and Printing Variables". Journal of Manufacturing and Materials Processing 8, n. 3 (31 maggio 2024): 118. http://dx.doi.org/10.3390/jmmp8030118.
Testo completoAbstract (sommario):
This research explores the utilization of powder fused filament fabrication (PFFF) for producing tungsten carbide-cobalt (WC-10Co) hardmetals, focusing on binder formulations and their impact on extrusion force as well as the influence of printing variables on the green and sintered density of samples. By examining the interplay between various binder compositions and backbone contents, this study aims to enhance the mechanical properties of the sintered parts while reducing defects inherent in the printing process. Evidence suggests that formulated feedstocks affect the hardness of the sintered hardmetal—not due to microstructural changes but macrostructural responses such as macro defects introduced during printing, debinding, and sintering of samples. The results demonstrate the critical role of polypropylene grafted with maleic anhydride (PP-MA) content in improving part density and sintered hardness, indicating the need for tailored thermal debinding protocols tailored to each feedstock. This study provides insights into feedstock formulation for hardmetal PFFF, proposing a path toward refining manufacturing processes to achieve better quality and performance of 3D printed hardmetal components.
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Wahyudi, Vritta Amroini, Noor Harini, Hanif Alamudin Manshur, Mochammad Wachid e Afifah Nuril Aini. "Study of Protein Concentrate from Flying Fish Roe Filament and its Application for Nutrified Rice-Corn Milk". Current Research in Nutrition and Food Science Journal 10, n. 2 (2 settembre 2022): 766–76. http://dx.doi.org/10.12944/crnfsj.10.2.29.
Testo completoAbstract (sommario):
One of the interesting marine products to be explored is flying fish (Hirundichthys oxycephalus) roes. The flying fish roe is usually called tobiko. The aim of this study is to extract protein from tobiko filaments using an isoelectric point approach, analyze their chemical properties, and apply them to the nutrification of rice-corn milk. Extraction of tobiko filaments using an isoelectric point approach resulted in an optimal pH of 8.5 based on the protein content (73.52 ± 0.07 %). Extraction under alkaline conditions (pH 8.5) resulted in a protein concentrate yield of 9.04% and an insoluble portion of 69.79%. That protein concentrate showed 15 amino acid, leucin (5.86 ± 0.01%), lycin (3.69 ± 0.02%), valin (3.41 ± 0.02%), isoleucine (3.33 ± 0.01%), threonine (2.86 ± 0.01%), phenylalanine (2.30 ± 0.02%), histidine (1.38 ± 0.01%), and methionine (1.21 ± 0.01%), glutamate (7.08 ± 0.01%), arginine (6.11 ± 0.01%), alanine (3.82 ± 0.01%), aspartic acid (3.75 ± 0.01%), serine (3.05 ± 0.02%), glycine (1.84 ± 0.01%), and tyrosine (1.46 ± 0.01%). The addition of protein concentrate from tobiko filament showed an increase in protein content in rice-corn milk so the purpose of nutrification in this study was successful. The best formulation is in the composition of rice: corn: protein concentrate (15:5:3%) with details of moisture content 65.07 ± 0.02%, ash content 0.50 ± 0.01%, the lipid content 0.28 ± 0.02%, the protein content 21.18 ± 0.02 %, the carbohydrate content 12.95 ± 0.02%, with a total energy 278.13 ± 0.03 kcal.
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Pflieger, Thomas, Rakesh Venkatesh, Markus Dachtler, Karin Eggenreich, Stefan Laufer e Dominique Lunter. "Novel Approach to Pharmaceutical 3D-Printing Omitting the Need for Filament—Investigation of Materials, Process, and Product Characteristics". Pharmaceutics 14, n. 11 (17 novembre 2022): 2488. http://dx.doi.org/10.3390/pharmaceutics14112488.
Testo completoAbstract (sommario):
The utilized 3D printhead employs an innovative hot-melt extrusion (HME) design approach being fed by drug-loaded polymer granules and making filament strands obsolete. Oscillatory rheology is a key tool for understanding the behavior of a polymer melt in extrusion processes. In this study, small amplitude shear oscillatory (SAOS) rheology was applied to investigate formulations of model antihypertensive drug Metoprolol Succinate (MSN) in two carrier polymers for pharmaceutical three-dimensional printing (3DP). For a standardized printing process, the feeding polymers viscosity results were correlated to their printability and a better understanding of the 3DP extrudability of a pharmaceutical formulation was developed. It was found that the printing temperature is of fundamental importance, although it is limited by process parameters and the decomposition of the active pharmaceutical ingredients (API). Material characterization including differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA) of the formulations were performed to evaluate component miscibility and ensure thermal durability. To assure the development of a printing process eligible for approval, all print runs were investigated for uniformity of mass and uniformity of dosage in accordance with the European Pharmacopoeia (Ph. Eur.).
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Kim, Young-Jin, Yu-Rim Choi, Ji-Hyun Kang, Yun-Sang Park, Dong-Wook Kim e Chun-Woong Park. "Geometry-Driven Fabrication of Mini-Tablets via 3D Printing: Correlating Release Kinetics with Polyhedral Shapes". Pharmaceutics 16, n. 6 (8 giugno 2024): 783. http://dx.doi.org/10.3390/pharmaceutics16060783.
Testo completoAbstract (sommario):
The aim of this study was to fabricate mini-tablets of polyhedrons containing theophylline using a fused deposition modeling (FDM) 3D printer, and to evaluate the correlation between release kinetics models and their geometric shapes. The filaments containing theophylline, hydroxypropyl cellulose (HPC), and EUDRAGIT RS PO (EU) could be obtained with a consistent thickness through pre-drying before hot melt extrusion (HME). Mini-tablets of polyhedrons ranging from tetrahedron to icosahedron were 3D-printed using the same formulation of the filament, ensuring equal volumes. The release kinetics models derived from dissolution tests of the polyhedrons, along with calculations for various physical parameters (edge, SA: surface area, SA/W: surface area/weight, SA/V: surface area/volume), revealed that the correlation between the Higuchi model and the SA/V was the highest (R2 = 0.995). It was confirmed that using 3D- printing for the development of personalized or pediatric drug products allows for the adjustment of drug dosage by modifying the size or shape of the drug while maintaining or controlling the same release profile.
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Thakkar, Rishi, Amit Raviraj Pillai, Jiaxiang Zhang, Yu Zhang, Vineet Kulkarni e Mohammed Maniruzzaman. "Novel On-Demand 3-Dimensional (3-D) Printed Tablets Using Fill Density as an Effective Release-Controlling Tool". Polymers 12, n. 9 (20 agosto 2020): 1872. http://dx.doi.org/10.3390/polym12091872.
Testo completoAbstract (sommario):
This research demonstrates the use of fill density as an effective tool for controlling the drug release without changing the formulation composition. The merger of hot-melt extrusion (HME) with fused deposition modeling (FDM)-based 3-dimensional (3-D) printing processes over the last decade has directed pharmaceutical research towards the possibility of printing personalized medication. One key aspect of printing patient-specific dosage forms is controlling the release dynamics based on the patient’s needs. The purpose of this research was to understand the impact of fill density and interrelate it with the release of a poorly water-soluble, weakly acidic, active pharmaceutical ingredient (API) from a hydroxypropyl methylcellulose acetate succinate (HPMC-AS) matrix, both mathematically and experimentally. Amorphous solid dispersions (ASDs) of ibuprofen with three grades of AquaSolveTM HPMC-AS (HG, MG, and LG) were developed using an HME process and evaluated using solid-state characterization techniques. Differential scanning calorimetry (DSC), powder X-ray diffraction (pXRD), and polarized light microscopy (PLM) confirmed the amorphous state of the drug in both polymeric filaments and 3D printed tablets. The suitability of the manufactured filaments for FDM processes was investigated using texture analysis (TA) which showed robust mechanical properties of the developed filament compositions. Using FDM, tablets with different fill densities (20–80%) and identical dimensions were printed for each polymer. In vitro pH shift dissolution studies revealed that the fill density has a significant impact (F(11, 24) = 15,271.147, p < 0.0001) and a strong negative correlation (r > −0.99; p < 0.0001) with the release performance, where 20% infill demonstrated the fastest and most complete release, whereas 80% infill depicted a more controlled release. The results obtained from this research can be used to develop a robust formulation strategy to control the drug release from 3D printed dosage forms as a function of fill density.
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Bagde, Arvind, Mina Messiha e Mandip Singh. "Development and Characterization of Cannabidiol Gummy Using 3D Printing". Gels 11, n. 3 (8 marzo 2025): 189. https://doi.org/10.3390/gels11030189.
Testo completoAbstract (sommario):
Oropharyngeal dysphagia and pain are prevalent concerns in the geriatric population. Therefore, this study investigates advances in the development of cannabidiol (CBD) gummies using 3D printing technology and compares them to commercially available molded gummies for pain management. A gelatin-based CBD formulation was prepared and printed using a syringe-based extrusion 3D printer. The formulation’s rheological properties were assessed, and the printed gummies were characterized using a texture analyzer. Drug content was analyzed using HPLC, and in vitro dissolution studies were conducted in phosphate buffer (pH 1.2 and 6.8). Our results demonstrated that the gelatin-based formulation had shear-thinning rheological properties for 3D printing at a temperature of 38.00 °C, filament diameter of 26 mm and flow of 110%. The optimized printing parameters produced gummies with higher elasticity compared to marketed gummies and comparable toughness. Drug content analysis showed 98.14 ± 1.56 and 97.97 ± 2.14% of CBD in 3D-printed and marketed gummies, respectively. Dissolution studies revealed that both gummy types released 100% of the drug within 30 min in both pH 1.2 and 6.8 buffers. Overall, 3D printing enables customizable CBD gummies with optimized release and offer a personalized and patient-friendly alternative to traditional oral forms for geriatric care.
33
Rogers, C. A., e C. E. Knight. "An axisymmetric linear/high-order finite element for filament-wound composites—I. Formulation and algorithm". Computers & Structures 29, n. 2 (gennaio 1988): 265–71. http://dx.doi.org/10.1016/0045-7949(88)90259-3.
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Cano, Santiago, Joamin Gonzalez-Gutierrez, Janak Sapkota, Martin Spoerk, Florian Arbeiter, Stephan Schuschnigg, Clemens Holzer e Christian Kukla. "Additive manufacturing of zirconia parts by fused filament fabrication and solvent debinding: Selection of binder formulation". Additive Manufacturing 26 (marzo 2019): 117–28. http://dx.doi.org/10.1016/j.addma.2019.01.001.
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Omer, Asma B., Farhat Fatima, Mohammed Muqtader Ahmed, Mohammed F. Aldawsari, Ahmed Alalaiwe, Md Khalid Anwer e Abdul Aleem Mohammed. "Enhanced Apigenin Dissolution and Effectiveness Using Glycyrrhizin Spray-Dried Solid Dispersions Filled in 3D-Printed Tablets". Biomedicines 11, n. 12 (18 dicembre 2023): 3341. http://dx.doi.org/10.3390/biomedicines11123341.
Testo completoAbstract (sommario):
This study aimed to prepare glycyrrhizin–apigenin spray-dried solid dispersions and develop PVA filament-based 3D printlets to enhance the dissolution and therapeutic effects of apigenin (APN); three formulations (APN1–APN3) were proportioned from 1:1 to 1:3. A physicochemical analysis was conducted, which revealed process yields of 80.5–91% and APN content within 98.0–102.0%. FTIR spectroscopy confirmed the structural preservation of APN, while Powder-XRD analysis and Differential Scanning Calorimetry indicated its transformation from a crystalline to an amorphous form. APN2 exhibited improved flow properties, a lower Angle of Repose, and Carr’s Index, enhancing compressibility, with the Hausner Ratio confirming favorable flow properties for pharmaceutical applications. In vitro dissolution studies demonstrated superior performance with APN2, releasing up to 94.65% of the drug and revealing controlled release mechanisms with a lower mean dissolution time of 71.80 min and a higher dissolution efficiency of 19.2% compared to the marketed APN formulation. This signified enhanced dissolution and improved therapeutic onset. APN2 exhibited enhanced antioxidant activity; superior cytotoxicity against colon cancer cells (HCT-116), with a lower IC50 than APN pure; and increased antimicrobial activity. A stability study confirmed the consistency of APN2 after 90 days, as per ICH, with an f2 value of 70.59 for both test and reference formulations, ensuring reliable pharmaceutical development. This research underscores the potential of glycyrrhizin–apigenin solid dispersions for pharmaceutical and therapeutic applications, particularly highlighting the superior physicochemical properties, dissolution behavior, biological activities, and stability of APN2, while the development of a 3D printlet shell offers promise for enhanced drug delivery and therapeutic outcomes in colon cancer treatment, displaying advanced formulation and processing techniques.
36
García-Ortiz, José Hermenegildo, e Francisco José Galindo-Rosales. "Extensional Magnetorheology as a Tool for Optimizing the Formulation of Ferrofluids in Oil-Spill Clean-Up Processes". Processes 8, n. 5 (17 maggio 2020): 597. http://dx.doi.org/10.3390/pr8050597.
Testo completoAbstract (sommario):
In this study, we propose a new way of optimising the formulation of ferrofluids for oil-spill clean-up processes, based on the rheological behaviour under extensional flow and magnetic fields. Different commercial ferrofluids (FFs), consisting of a set of six ferrofluids with different magnetic saturation and particle concentration, were characterised in a Capillary Break-Up Extensional Rheometer (CaBER) equipped with two magnetorheological cells that allow imposing a homogeneous and tunable magnetic field either parallel or perpendicular to the flow direction. The filament thinning process with different intensities and orientation of the magnetic field with respect to the flow direction was analysed, and the results showed that the perpendicular configuration did not have a significant effect on the behaviour of the ferrofluids, as in shear magnetorheometry. However, the parallel configuration allowed to determine that the formulation of ferrofluids for oil-spill cleaning processes should consist of a 4% vol concentration of magnetic nanoparticles with a magnetic saturation of M s > 20 mT.
37
Mazzanti, Valentina, Lorenzo Malagutti e Francesco Mollica. "FDM 3D Printing of Polymers Containing Natural Fillers: A Review of their Mechanical Properties". Polymers 11, n. 7 (28 giugno 2019): 1094. http://dx.doi.org/10.3390/polym11071094.
Testo completoAbstract (sommario):
As biodegradable thermoplastics are more and more penetrating the market of filaments for fused deposition modeling (FDM) 3D printing, fillers in the form of natural fibers are convenient: They have the clear advantage of reducing cost, yet retaining the filament biodegradability characteristics. In plastics that are processed through standard techniques (e.g., extrusion or injection molding), natural fibers have a mild reinforcing function, improving stiffness and strength, it is thus interesting to evaluate whether the same holds true also in the case of FDM produced components. The results analyzed in this review show that the mechanical properties of the most common materials, i.e., acrylonitrile-butadiene-styrene (ABS) and PLA, do not benefit from biofillers, while other less widely used polymers, such as the polyolefins, are found to become more performant. Much research has been devoted to studying the effect of additive formulation and processing parameters on the mechanical properties of biofilled 3D printed specimens. The results look promising due to the relevant number of articles published in this field in the last few years. This notwithstanding, not all aspects have been explored and more could potentially be obtained through modifications of the usual FDM techniques and the devices that have been used so far.
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Ahn, Dae Keon, Jin Hwe Kweon, Jin Ho Choi e Seok Hee Lee. "Relation between Surface Roughness and Overlap Interval in Fused Deposition Modeling". Advanced Materials Research 264-265 (giugno 2011): 1625–30. http://dx.doi.org/10.4028/www.scientific.net/amr.264-265.1625.
Testo completoAbstract (sommario):
Rapid prototyping (RP) can efficiently fabricate high level models with complex shapes. Hence the RP has been widely applied in various industrial fields. However, as the technology is inherently performed by layered manufacturing process, the surface quality of the RP part is not satisfactory to use general industrial purpose. This is the reason that surface roughness problem has been key issue in RP. In this paper, relation between surface roughness and overlap interval is investigated based on a surface roughness formulation in fused deposition modeling (FDM). Additionally, effects of surface angle and filament shape are analyzed and discussed to predict surface roughness distribution by the overlap interval variation.
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Abderrafai, Yahya, Mohammad Hadi Mahdavi, Facundo Sosa-Rey, Chloé Hérard, Ivonne Otero Navas, Nicola Piccirelli, Martin Lévesque e Daniel Therriault. "Additive manufacturing of short carbon fiber-reinforced polyamide composites by fused filament fabrication: Formulation, manufacturing and characterization". Materials & Design 214 (febbraio 2022): 110358. http://dx.doi.org/10.1016/j.matdes.2021.110358.
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Jo, Aeree, Heedo Chae, Yongjun Kim, Heeju Kim, Seunghwi Paek, Veasna Soum, Wonhyeong Jang, Soo Ryeon Ryu, Oh-Sun Kwon e Kwanwoo Shin. "Formulation of Conductive Filament Composited of Thermoplastic with Carbon Black for a Simple 3D Printing Electrical Device". Journal of Nanoscience and Nanotechnology 16, n. 8 (1 agosto 2016): 8415–18. http://dx.doi.org/10.1166/jnn.2016.12532.
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Van Gorder, Robert A. "Quantum vortex dynamics under the tangent representation of the local induction approximation". Journal of Fluid Mechanics 740 (10 gennaio 2014): 5–16. http://dx.doi.org/10.1017/jfm.2013.626.
Testo completoAbstract (sommario):
AbstractWe derive the local induction approximation (LIA) for a quantum vortex filament in the arclength coordinate frame where the tangent vector is the unknown function. The equation for the tangent vector to the filament is then converted to a potential form, which ends up being a type of nonlinear Schrödinger equation that governs the tangential LIA model (T-LIA). Such a formulation was previously derived by Umeki for the standard fluid model (in the absence of superfluid friction terms). While it is challenging to generalize many of the exact solutions found for the standard LIA to the quantum LIA model, we demonstrate that the T-LIA model facilitates this generalization nicely. Indeed, under the T-LIA model, we are able to construct a variety of solutions. The Hasimoto solution related to elastica is one of the fundamental solutions present for the standard fluid model; however, using the T-LIA model, we are able to demonstrate the existence of such a solution, thereby extending the Hasimoto solution to the superfluid case. In the zero-temperature limit, purely self-similar solutions are shown to exist for the T-LIA model. As the superfluid warms (so that the influence of the normal flow is no longer negligible), the analogue to the self-similar solution is a new class of solutions, which depend on the similarity variable as well as a time-dependent additive scaling. In other words, the self-similar structures gradually deform as the magnitude of the normal-fluid velocity increases, which makes complete physical sense. When dealing with small deviations from the central axis of alignment, we can describe such solutions analytically. There exists a family of helical vortex filaments in the presence of a normal fluid impinging on the vortex, in complete agreement with the previously studied results for the LIA model. Finally, a number of soliton solutions are shown to exist in different regimes of the T-LIA model.
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Di, Chengrui, Junwei Yu, Baoming Wang, Alan Kin Tak Lau, Bo Zhu e Kun Qiao. "Study of Hybrid Nanoparticles Modified Epoxy Resin Used in Filament Winding Composite". Materials 12, n. 23 (22 novembre 2019): 3853. http://dx.doi.org/10.3390/ma12233853.
Testo completoAbstract (sommario):
Hybrid nanoparticles modified bisphenol A type epoxy/acid anhydride resin system applicable for filament winding forming process was studied using elastic core-shell rubber (CSR) nanoparticles with a large particle size (nearly 100 nm) and rigid nano-SiO2 particles with a small particle size (about 16 nm). The formulation, process properties, mechanical properties, thermal properties and microstructure of modified resin and its wound composite were studied. The results suggested that at the content of 10 phr CSR and 2 phr nano-SiO2, the resin system achieved optimum comprehensive performance. The viscosity of modified resin system was nearly 1000 mPa·s at 25 °C and service life was over 6 h. The resin tensile strength and modulus were 89 MPa and 3.5 GPa, while flexural strength and modulus reached 128 MPa and 3.2 GPa, respectively. The impact strength was 26.6 kJ·m−2, and the glass transition temperature (Tg) reached 145.9 °C. Modified epoxy resin enhanced the mechanical properties of carbon fiber reinforced wound composite. The tensile strength, tensile modulus and interlaminar shear strength were enhanced by 14.0%, 4.56% and 18.9%, respectively, compared with a composite based on unmodified resin. The above test results and scanning electron microscopy (SEM) analysis suggest that the hybrid nanoparticles modified resin system was suitable for carbon fiber wet filament winding products.
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Stango, R. J., H. Zhao e C. Y. Shia. "Analysis of Contact Mechanics for Rotor-Bristle Interference of Brush Seal". Journal of Tribology 125, n. 2 (19 marzo 2003): 414–21. http://dx.doi.org/10.1115/1.1510879.
Testo completoAbstract (sommario):
Brush seals have proven to be an attractive alternative to labyrinth seals for turbomachinery applications. This innovation in seal technology utilizes both the high temperature capability of special-alloy wire and the flexural adaptability of fibers to accommodate a wide range of operating conditions that are encountered during service. The effectiveness of the seal is principally derived from the bristles ability to endure forces imparted by both the fluid and shaft, and yet maintain contact between the filament tips and the surface of the rotor. Consequently, contact forces generated along the interface of the fiber tip and rotor are an important consideration for both the design and performance of the rotor-seal assembly. This paper focuses on evaluating brush seal forces that arise along the surface of the rotor due to the dimensional disparity or interference between the rotor-fiber. Filament tip contact forces are computed on the basis of an in-plane, large deformation mechanics analysis of a cantilever beam, and validation of the model is assessed by using an electronic balance for measuring the shear and normal force exerted by a bristle tip onto a flat, hardened surface. Formulation of the mechanics problem is briefly reviewed, and includes the effect of Coulombic friction at the interface of the fiber tip and rotor. Filament contact force is used as a basis for computing bearing stress along the fiber-rotor interface. Results are reported for a range of brush seal design parameters in order to provide a better understanding of the role that seal geometry, friction, and bristle flexural rigidity play in generating rotor contact force.
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Jin, Shi, Xuelei Wang e Thomas L. Starr. "A model for front evolution with a nonlocal growth rate". Journal of Materials Research 14, n. 10 (ottobre 1999): 3829–32. http://dx.doi.org/10.1557/jmr.1999.0515.
Testo completoAbstract (sommario):
In this paper we provide a new mathematical model for front propagation with a nonlocal growth law in any space dimension. Such a problem arises in composite fabrication using the vapor infiltration process and in other physical problems involving transport and reaction. Our model, based on the level set equation coupled with a boundary value problem of the Laplace equation, is an Eulerian formulation, which allows robust treatment for topological changes such as merging and formation of pores without artificially tracking them. When applied to the fabrication of continuous filament ceramic matrix composites using chemical vapor infiltration, this model accurately predicts not only residual porosity but also the precise locations and shapes of all pores.
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ANDERSEN, MORTEN, e MORTEN BRØNS. "Topology of helical fluid flow". European Journal of Applied Mathematics 25, n. 3 (17 marzo 2014): 375–96. http://dx.doi.org/10.1017/s0956792514000084.
Testo completoAbstract (sommario):
Considering a coordinate-free formulation of helical symmetry rather than more traditional definitions based on coordinates, we discuss basic properties of helical vector fields and compare results from the literature obtained with other approaches. In particular, we discuss the role of the stream function for the topology of the streamline pattern in incompressible flows. On this basis, we perform a comprehensive study of the topology of the flow field generated by a helical vortex filament in an ideal fluid. The classical expression for the stream function obtained by Hardin (Hardin, J. C. 1982 Phys. Fluids25, 1949–1952) contains an infinite sum of modified Bessel functions. Using the approach by Okulov (Okulov, V. L. 1995 Russ. J.Eng. Thermophys.5, 63–75) we obtain a closed-form approximation which is considerably easier to analyse. Critical points of the stream function can be found from the zeroes of a single real function of one variable, and we show that three different flow topologies can occur, depending on a single dimensionless parameter. By including the self-induced velocity on the vortex filament by a localised induction approximation, the stream function is slightly modified and an extra parameter is introduced. In this setting two new flow topologies arise, but not more than two critical points occur for any combination of parameters.
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Cavallo, Aida, Giorgia Radaelli, Tamer Al Kayal, Angelica Mero, Andrea Mezzetta, Lorenzo Guazzelli, Giorgio Soldani e Paola Losi. "Optimization of Gelatin and Crosslinker Concentrations in a Gelatin/Alginate-Based Bioink with Potential Applications in a Simplified Skin Model". Molecules 30, n. 3 (1 febbraio 2025): 649. https://doi.org/10.3390/molecules30030649.
Testo completoAbstract (sommario):
Three-dimensional bioprinting allows for the fabrication of structures mimicking tissue architecture. This study aimed to develop a gelatin-based bioink for a bioprinted simplified skin model. The bioink printability and chemical-physical properties were evaluated by varying the concentrations of gelatin (10, 15, and 20%) in a semi-crosslinked alginate-based bioink and calcium chloride (100, 150, and 200 mM) in post-printing crosslinking. For increasing the gelatin concentration, the gelatin-based formulations have a shear thinning behavior with increasing viscosity, and the filament bending angle increases, the spreading ratio value approaches 1, and the shape fidelity and the printing resolution improve. However, the formulation containing 20% of gelatin was not homogeneous, resulting also in poor printability properties. The morphology of the pores, degradation, and swelling depend on gelatin and CaCl2 concentrations, but not in a significant way. The samples containing 15% of gelatin and crosslinked with 150 mM CaCl2 have been selected for the bioprinting of a bilayer skin model containing human fibroblasts and keratinocytes. The model showed a homogeneous distribution of viable and proliferating cells over up to 14 days of in vitro culture. The gelatin-based bioink allowed for the 3D bioprinting of a simplified skin model, with potential applications in the bioactivity of pro-reparative molecules and drug evaluation.
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Qian, Haonan, Di Chen, Xiangyu Xu, Rui Li, Guangrong Yan e Tianyuan Fan. "FDM 3D-Printed Sustained-Release Gastric-Floating Verapamil Hydrochloride Formulations with Cylinder, Capsule and Hemisphere Shapes, and Low Infill Percentage". Pharmaceutics 14, n. 2 (25 gennaio 2022): 281. http://dx.doi.org/10.3390/pharmaceutics14020281.
Testo completoAbstract (sommario):
The aim of this work was to design and fabricate fused deposition modeling (FDM) 3D-printed sustained-release gastric-floating formulations with different shapes (cylinder, capsule and hemisphere) and infill percentages (0% and 15%), and to investigate the influence of shape and infill percentage on the properties of the printed formulations. Drug-loaded filaments containing HPMC, Soluplus® and verapamil hydrochloride were prepared via hot-melt extrusion (HME) and then used to print the following gastric-floating formulations: cylinder-15, capsule-0, capsule-15, hemisphere-0 and hemisphere-15. The morphology of the filaments and the printed formulations were observed by scanning electron microscopy (SEM). The physical state of the drugs in the filaments and the printed formulations were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The printed formulations were evaluated in vitro, including the weight variation, hardness, floating time, drug content and drug release. The results showed that the drug-loaded filament prepared was successful in printing the gastric floating formulations. Verapamil hydrochloride was proved thermally stable during HME and FDM, and in an amorphous state in the filament and the printed formulations. The shape and infill percentage of the printed formulations effected the hardness, floating time and in vitro drug release.
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Maurel, Alexis, Roberto Russo, Sylvie Grugeon, Stéphane Panier e Loic Dupont. "Environmentally Friendly Lithium-Terephthalate/Polylactic Acid Composite Filament Formulation for Lithium-Ion Battery 3D-Printing via Fused Deposition Modeling". ECS Journal of Solid State Science and Technology 10, n. 3 (1 marzo 2021): 037004. http://dx.doi.org/10.1149/2162-8777/abedd4.
Testo completo
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Keylock, Christopher J. "Turbulence at the Lee bound: maximally non-normal vortex filaments and the decay of a local dissipation rate". Journal of Fluid Mechanics 881 (24 ottobre 2019): 283–312. http://dx.doi.org/10.1017/jfm.2019.779.
Testo completoAbstract (sommario):
This paper uses a tight mathematical bound on the degree of the non-normality of the turbulent velocity gradient tensor to classify flow behaviour within vortical regions (where the eigenvalues of the tensor contain a conjugate pair). Structures attaining this bound are preferentially generated where enstrophy exceeds total strain and there is a positive balance between strain production and enstrophy production. Lagrangian analysis of homogeneous, isotropic turbulence shows that attainment of this bound is associated with relatively short durations and an upper limit to the spatial extent of the flow structures that is similar to the Taylor scale. An analysis of the dynamically relevant terms using a recently developed formulation (Keylock, J. Fluid Mech., vol. 848, 2018, pp. 876–904), highlights the controls on this dynamics. In particular, in high enstrophy regions it is shown that the bound is attained when normal strain decreases rather than when non-normality increases. The near absence of normal total strain results in a source of intermittency in the dynamics of dissipation that is hidden in standard analyses. It is shown that of the two terms that contribute to the non-normal production dynamics, it is the one that is typically smallest in magnitude that is of greatest importance within these $\ell =1$ filaments. The typical distance between filament centroids is just less than a Taylor scale, implying a connection to the manner in which flow topology at the Taylor scale explains dissipation at smaller scales.
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Wang, Fei, Qianfeng Zhou, Zhe Zhang, Yonghua Gu, Jiliang Zhang e Kaiyong Jiang. "Microwave Absorption Properties of Carbon Black-Carbonyl Iron/Polylactic Acid Composite Filament for Fused Deposition Modeling". Materials 15, n. 15 (8 agosto 2022): 5455. http://dx.doi.org/10.3390/ma15155455.
Testo completoAbstract (sommario):
A single microwave absorbent and simple coating structure cannot meet the increasing requirements for broadband and strong absorption. Three-dimensional printing is an effective way to prepare multi-component complex structure metamaterial absorbers, and the key is to prepare raw materials with excellent absorption properties, suitable for 3D printing. In this paper, CB-CIP/PLA composite filament was prepared via a high-energy mixer and twin-screw extruder by compounding the dielectric loss material carbon black (CB) and the magnetic loss material carbonyl iron powder (CIP) with polylactic acid (PLA) as the matrix. The coaxial ring test piece was printed by FDM technology, and the microstructure of the composites was observed and analyzed by SEM. Meanwhile, the electromagnetic parameters of the composites were examined by a vector network analyzer, mainly studying the influence of the CB and CIP content and thickness on the microwave absorbing properties of the composite material. The results show that when the CB content is 20% and the CIP content is 30%, the CB-CIP/PLA composite has excellent microwave absorption and broad bandwidth. When the matching thickness is 1.6 mm, the minimum reflection loss (RL) reaches −51.10 dB; when the thickness is 1.7 mm, the effective absorption bandwidth (RL < −10 dB) is 5.04 GHz (12.96–18 GHz), nearly covering the whole Ku band. This work provides an efficient formulation and process to prepare an absorbing composite filament for FDM.