Plasma and Electrospray Deposition to Improve the Biocompatibility of Stents

2007 ◽  
Vol 539-543 ◽  
pp. 529-534 ◽  
Author(s):  
Michael Tatoulian ◽  
Enrico Gallino ◽  
R. Jafari ◽  
Farzaneh Arefi-Khonsari ◽  
L. Tatoulian ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Three Dimensional ◽  
Film Coating ◽  
Polymer Coatings ◽  
The Body ◽  
Metallic Ions ◽  
Ion Release ◽  
Three Dimensional Objects ◽  
Intravascular Stents ◽  
The Stability

Metallic Intravascular stents are medical devices used to scaffold a biological lumen, mostly diseased arteries, after balloon angioplasty. They are commonly made of 316L stainless steel or Nitinol, two alloys containing Nickel, an element classified as potentially toxic and carcinogenic. Although they are largely implanted, the long-term safety of such metallic elements is still controversial, since the corrosion processes may lead to the release of several metallic ions. In order to avoid the metallic ion release in the body and to improve the biocompatibility of metallic stents with their biological environments, polymer coatings have been deposited by two different technologies, i.e. plasma surface modifications and Electrospraying. The role of the polymer coating is then to encapsulate the stainless steel device, and to favour the chemical grafting of Phosphorylcholine, a molecule known for its hemocompatible properties.1 In this talk, the state of the art on low pressure and atmospheric pressure plasmas for deposition of organic coatings will be given and we will present the advantages and drawbacks of each process. Then, we will present an original technology that combine a Dielectric Barrier Discharge and an electrospraying system to deposit well-defined Polyacrylic acid and Polyallylamine films. The advantage of such system is the possibility to limit the extent of the monomer fragmentation and to give rise to rapid deposition of a highly functionalised plasma polymer layer, and also the possibility to cover three dimensional objects, such as stents. Thus, the theory of EHDA technology will be explained: special attention has been paid to define the Electrospray parameters (Voltage, flow of precursor, nozzle-substrate distance…) which control the size distribution of the charged droplets and as a consequence, the structure of the film coating. The film coatings have been analysed with XPS and by ATR. Moreover, special attention will be paid on the stability of the coating which is related to both spraying conditions as well as to the preliminary plasma treatment. The potentiality and the features of the EHDA process will be then presented.

scholarly journals A pilot study on the use of 3D printers in veterinary medicine

2021 ◽  
Vol 14 (3) ◽  
pp. 159-164
Author(s):  
Leonardo Leonardi ◽  
◽  
Roberto Marsili ◽  
Enrico Bellezza ◽  
Giovanni Angeli ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Bone Tissue ◽  
Three Dimensional ◽  
The Body ◽  
Porous Scaffolds ◽  
Layer By Layer ◽  
Three Dimensional Objects ◽  
Cellular Attachment

Additive manufacturing (AM) is the process of joining materials to create layer-by-layer three-dimensional objects using a 3D printer from a digital model. The great advantage of Additive Manufacturing is to allow a freer design than traditional processes. The development of additive manufacturing processes has permitted to optimize the production of the customized product through the modeling of the geometry and the knowledge of the morphometric parameters of the body structures. 3D printing has revolutionized the field of Regenerative Medicine because, starting from computerized tomography (CT) images and using traditional materials such as plastic and metals, it can provide customized prostheses for each patient, which adapt perfectly to the needs of the subject and act as structures support. 3D printing allows you to print three-dimensional porous scaffolds with a precise shape and chemical composition suitable for medical and veterinary use. Some of these scaffolds are biodegradable and appear to be ideal for bone tissue engineering. In fact, they are able to simulate extracellular matrix properties that allow mechanical support, favoring mechanical interactions and providing a model for cellular attachment and in vivo stimulation of bone tissue formation.

scholarly journals Self-Limiting Electrospray Deposition for the Surface Modification of Additively Manufactured Parts

2019 ◽  
Author(s):  
Dylan A. Kovacevich ◽  
Lin Lei ◽  
Daehoon Han ◽  
Christianna Kutznetsova ◽  
Howon Lee ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Spray Coating ◽  
The Body ◽  
Line Of Sight ◽  
Electrospray Deposition ◽  
Three Dimensional Objects ◽  
Humidity Response ◽  
Surface Functionality ◽  
Over Time ◽  
Flowing Solution

Electrospray deposition (ESD) is a spray coating process that utilizes a high voltage to atomize a flowing solution into charged microdroplets. These self-repulsive droplets evaporate as they travel to a target substrate, depositing the solution solids. Our previous research investigated the conditions necessary to minimize charge dissipation and deposit a thickness-limited film that grows in area over time through self-limiting electrospray deposition (SLED). Such sprays possess the ability to conformally coat complex three-dimensional objects without changing the location of the spray needle or orientation of the object. This makes them ideally suited for the post-processing of materials fabricated through additive manufacturing (AM), opening a paradigm of independent bulk and surface functionality. Having demonstrated three-dimensional coating with film thickness in the range of 1-50 µm on a variety of conductive objects, in this study we employed model substrates to quantitatively study the technique’s limits with regard to geometry and scale. Specifically, we examined the effectiveness of thickness-limited ESD for coating recessed features with gaps ranging from 50 µm to 1 cm, as well as the ability to coat surfaces hidden from the line-of-sight of the spray needle. This was then extended to the coating of hydrogel structures printed by AM, demonstrating that coating could be conducted even into the body of the structures as a means to create hydrophobic surfaces without affecting the absorption-driven humidity response.

On the Stability of Rotation of a Rotor With Rotationally Unsymmetric Inertia and Stiffness Properties

1961 ◽  
Vol 28 (4) ◽  
pp. 567-570 ◽  
Author(s):  
S. H. Crandall ◽  
P. J. Brosens
Keyword(s):  
Three Dimensional ◽  
The Body ◽  
Uniform Rotation ◽  
Stiffness Properties ◽  
Principal Axes ◽  
Rotationally Symmetric ◽  
Speed Range ◽  
Stiffness Characteristics ◽  
The Stability ◽  
Gyroscopic Coupling

The stability of uniform rotation of a rigid body about a principal axis of inertia is analyzed for the case where there is a diametral inertia inequality and there is an elastic restoring mechanism with a diametral stiffness inequality which rotates with the body. This model is an idealization for systems such as a two-bladed propeller rotating on a flexible shaft whose stiffness characteristics are not rotationally symmetric. It is found that many such systems possess unstable speed ranges. The instability may be due to either type of asymmetry alone or due to the interaction of the two. Quantitative analytical results are obtained which relate the unstable speed range to the gyroscopic coupling, the inertia inequality, the stiffness inequality, and the relative orientation of the principal axes of inertia with respect to the principal axes of stiffness. Three-dimensional stability surfaces are plotted to give a qualitative overview of the interplay of the various parameters.

Moving around Objects and Recognizing Them

1998 ◽  
Vol 86 (1) ◽  
pp. 267-276 ◽  
Author(s):  
F. Giusberti ◽  
T. Iachini ◽  
F. Pavani
Keyword(s):  
Mental Rotation ◽  
Spatial Information ◽  
Angular Displacement ◽  
Three Dimensional ◽  
Linear Increase ◽  
The Body ◽  
Experimental Task ◽  
Three Dimensional Objects ◽  
Spatial Properties ◽  
Rotated Objects

This research concerned the use of mental rotation in recognizing rotated objects. Instead of the classic Shepard's paradigm in which subjects were still while observing rotated objects, here subjects had to move (or imagine moving) around stationary three-dimensional objects put in the middle of the trajectory. Thus, depending on the viewing positions, such objects were seen under six different perspectives (from 30° to 180°). The latter task has been thought to be closer to everyday life in which we obtain information regarding objects from their spatial properties. The results do not follow the classic rules of mental rotation of an object predicting a linear increase of the time needed to recognize distorted objects as a function of their angular displacement. They also differ from data in the Literature about spatial imagery showing that access to spatial information is facilitated more when people actually move through a path than when they imagine moving. A probable explanation of this difference from the literature is discussed in relation to the particular involvement of the body in the experimental task.

Manipulation with a polyarticulated mechanical hand: a new efficient real-time method for computing fingertip forces for a global manipulation strategy

Robotica ◽  
2005 ◽  
Vol 23 (4) ◽  
pp. 479-490 ◽  
Author(s):  
J. P. Gazeau ◽  
S. Zeghloul ◽  
G. Ramirez
Keyword(s):  
Optimization Problem ◽  
Three Dimensional ◽  
Inequality Constraints ◽  
Minimal Distance ◽  
Linear Quadratic ◽  
New Approach ◽  
Three Dimensional Objects ◽  
Mechanical Hand ◽  
The Stability ◽  
Manipulation Strategy

This paper proposes an efficient algorithm for computing finger forces involved in a three-dimensional objects grasp. Effective finger force computation is necessary for the successful manipulation on an object by a multifingered robot hand. Based on previous works, the stability forces are computed as a solution of an optimization problem. This optimization problem is mapped into a linear quadratic problem under inequality constraints. We propose a new approach for this problem: the problem is solved as a minimal distance calculation problem in the forces space. The results obtained by simulation demonstrate the efficiency and the numerical stability of the method. This method is used with the LMS mechanical hand as a component of the global control strategy dedicated to the object manipulation.

Solute Segregation in Stainless Steel under Irradiation

1977 ◽  
Vol 35 ◽  
pp. 46-47
Author(s):  
Edward A. Kenik
Keyword(s):  
Stainless Steel ◽  
Ion Irradiation ◽  
Three Dimensional ◽  
Void Formation ◽  
Dislocation Loops ◽  
Nickel Ion ◽  
316 Stainless Steel ◽  
Prime Concern ◽  
Radiation Induced ◽  
The Stability

Solute element additions can significantly influence the behavior of an alloy under irradiation. The aggregation of irradiation-induced vacancies into three-dimensional clusters, voids, and the volume expansion, swelling, associated with void formation is of prime concern in the design of nuclear reactors. A modified type 316 stainless steel, LS1A, has been developed which exhibits high resistance to swelling. This alloy, containing ˜1.0 wt % silicon and 0. 15 wt % titanium, swells 30 times less under nickel ion irradiation than a nominal type 316 stainless steel.In addition to the observation of swelling resistance in LS1A, it was observed that the evolution of dislocation portions of the damage structure was modified by the silicon and titanium additions. Specifically, the stability of faulted dislocation loops in LS1A is quite high and the growth of large loops is severely curtailed. At higher doses, radiation-induced precipitates of the same size and shape as the dislocation loops were observed.

Visual Rhetoric

2018 ◽  
Author(s):  
Zazil Reyes García
Keyword(s):  
Visual Rhetoric ◽  
Three Dimensional ◽  
The Body ◽  
Visual Images ◽  
Late 20Th Century ◽  
Three Dimensional Objects ◽  
Video Advertising ◽  
The World ◽  
Visual Artifacts ◽  
Written Word

The growing field of visual rhetoric explores the communicative and persuasive power of the visual artifacts that surround us. This relatively new branch of rhetoric emerged in the late 20th century, disrupting a discipline that was traditionally concerned with the spoken and written word. The artifacts studied through the lens of visual rhetoric comprise visual images and objects that are human created and culturally meaningful. They include two-dimensional images, such as political cartoons and video advertising, and three-dimensional objects such as museums and murals. Visual rhetoric can also include the analysis of embodied performance and thus examine the body as argument. Although much of the scholarship focuses on the power of images in shaping people’s understanding of the world, there is also a recognition of the power of looking. Meaning does not reside in the images around us; we participate in its construction. To better understand visual rhetoric, it is important to review its emergence as an area of study, its definitions, and some of the recurring themes in the scholarship.

scholarly journals Numerical Modeling and Stability Analysis of Surrounding Rock of Yuanjue Cave

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zhigang Meng ◽  
Fangzheng Fan ◽  
Xuebin Cui ◽  
Shu Tao ◽  
Yi Cao
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Lower Layer ◽  
Three Dimensional ◽  
Surrounding Rock ◽  
The Body ◽  
Adjacent Area ◽  
The West ◽  
Monitoring Point ◽  
The Stability

Yuanjue Cave, located in Big Buddha Bay, Mount Baoding, Dazu Rock Carvings Area, has extremely high historical, artistic, and religious value and is an important grotto cultural relic in China. Due to the cutting action of the fissures and weak interlayers, the South Cliff of Big Buddha Bay where Yuanjue Cave is located showed signs of instability. In order to fully evaluate the stability of the rock mass around the cliff where Yuanjue Cave is located, a three-dimensional geological model of the surrounding rock of Yuanjue Cave was established by using FLAC3D software, combined with three-dimensional scanning, fissure investigation, and indoor tests. The stability of the surrounding rock mass adjacent to Yuanjue Cave has been studied by precise numerical simulation, and the results of numerical simulation and monitoring have been compared and analysed. The results show the following: (1) The west of J10 fissure, above the mudstone interlayer, is the main deformation area. The cliff displacement increases gradually from the east to the west. The independent block above the corner has the largest free space displacement, and there is a risk of independent collapse. Special attention should be paid to the stability of this block. The displacement of the upper monitoring point of the cliff wall is significantly greater than that of the lower layer. (2) In the surrounding rock block in the adjacent area, the various concentrated stresses of the body are mainly located at the entrance of Yuanjue Cave, the height of the chest of the Zhengjue Buddha statue, and the lower mudstone erosion and reinforcement zone. Among them, the stress concentration in the erosion and reinforcement area under the Zhengjue Buddha statue is the largest. The conclusions obtained can provide a useful reference for the stability assessment of the surrounding rock of Yuanjue Cave.

scholarly journals Kinematic and Aerodynamic Investigation of the Butterfly in Forward Free Flight for the Butterfly-Inspired Flapping Wing Air Vehicle

2021 ◽  
Vol 11 (6) ◽  
pp. 2620
Author(s):  
Yixin Zhang ◽  
Xingjian Wang ◽  
Shaoping Wang ◽  
Wenhao Huang ◽  
Qiwang Weng
Keyword(s):  
High Speed ◽  
Kinematic Model ◽  
Three Dimensional ◽  
Flapping Wing ◽  
The Body ◽  
Main Body ◽  
Free Flight ◽  
Forward Flight ◽  
The Stability ◽  
Generation Mechanisms

To ensure the stability of flight, the butterfly needs to flap its wings and simultaneously move its main body to achieve all kinds of flying motion, such as taking off, hovering, or reverse flight. The high-speed camera is used to record the swing of the abdomen, the movement of the wings, and the pitch angle of the body for butterflies during their free flight; the comprehensive biokinetic observations show that the butterfly’s wings and body are coupled in various flight states. The swing of the abdomen and the flap of the fore wing affect the pitch motion significantly. For theoretical analysis of the butterfly flight, a three-dimensional multi-rigid butterfly model based on real butterfly dimension is established, and the aerodynamic of the butterfly flight is simulated and analyzed via computational fluid dynamics methods to obtain an optimal kinematic model of butterfly forward flight. Moreover, the formation and development of three-dimensional vortex structures in the forward flight are also presented. The detailed structures of vortices and their dynamic behavior show that the wing’s flap and the abdominal swing play a key role in reorienting and correcting the “clap and peel” mechanism, and the force generation mechanisms are evaluated. The research indicates that longitudinal flight performance is mainly related to the kinematic parameters of the wing and body, and it can lead to the development of butterfly-inspired flapping wing air vehicles.

scholarly journals Self-Limiting Electrospray Deposition for the Surface Modification of Additively Manufactured Parts

2019 ◽  
Author(s):  
Dylan A. Kovacevich ◽  
Lin Lei ◽  
Daehoon Han ◽  
Christianna Kutznetsova ◽  
Howon Lee ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Spray Coating ◽  
The Body ◽  
Line Of Sight ◽  
Electrospray Deposition ◽  
Three Dimensional Objects ◽  
Humidity Response ◽  
Surface Functionality ◽  
Over Time ◽  
Flowing Solution

Electrospray deposition (ESD) is a spray coating process that utilizes a high voltage to atomize a flowing solution into charged microdroplets. These self-repulsive droplets evaporate as they travel to a target substrate, depositing the solution solids. Our previous research investigated the conditions necessary to minimize charge dissipation and deposit a thickness-limited film that grows in area over time through self-limiting electrospray deposition (SLED). Such sprays possess the ability to conformally coat complex three-dimensional objects without changing the location of the spray needle or orientation of the object. This makes them ideally suited for the post-processing of materials fabricated through additive manufacturing (AM), opening a paradigm of independent bulk and surface functionality. Having demonstrated three-dimensional coating with film thickness in the range of 1-50 µm on a variety of conductive objects, in this study we employed model substrates to quantitatively study the technique’s limits with regard to geometry and scale. Specifically, we examined the effectiveness of thickness-limited ESD for coating recessed features with gaps ranging from 50 µm to 1 cm, as well as the ability to coat surfaces hidden from the line-of-sight of the spray needle. This was then extended to the coating of hydrogel structures printed by AM, demonstrating that coating could be conducted even into the body of the structures as a means to create hydrophobic surfaces without affecting the absorption-driven humidity response.

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