A clinical and experimental study of jet injections

Thesis (M.Sc.D.)--Boston University School of Graduate Dentistry, 1973. Oral Biology.Bibliography included.Since the jet injection was clinically introduced in 1947, little work has been done to evaluate the tissue response to the technique. The present investigation compares the tissue reaction of the jet injections to that of needle injections. The animal investigation was carried out on 30 adult rats, divided into four groups, using a tuberculin syringe with a 26 gauge needle on the control side and a Syrijet Mark II on the experimental. The first group of 18 rats was injected with saline and sacrificed two at a time immediately and at one, two, three, four, six, twelve, twenty-four and forty-eight hours. The second group of eight rats was injected with saline and sacrificed one at a time at two, three, four, six, twelve, twenty-four and forty-eight hours. Prior to sacrifice this group received intraperitoneal injections of trypan blue at half-hourly intervals for a total of three injections and was sacrificed half an hour after the last injection. The third group of two rats received trypan blue injections instead of saline and were sacrificed immediately. The fourth group of two rats was injected with India ink and sacrificed immediately. Stereoscopic and histological examination revealed that injected solutions invariably follow the lines of least resistance in the connective tissues and muscles. Both techniques demonstrate areas of hemorrhage and disruption of connective tissue fibres and displacement of epithelial cells into the underlying connective tissues. An acute inflammatory reaction and damaged connective tissue and muscle fibres was observed following injection techniques. Resolution was rooted in most cases within 48 hours

Cytocompatibility of vitreous carbon as a dental implant

Thesis (D.Sc.D.)--Boston University, School of Graduate Dentistry, 1974.Bibliography included

Enhancing Grasp Pose Computation in Gripper Workspace Spheres

In this paper, enhancement to the novel grasp planning algorithm based on gripper workspace spheres is presented. Our development requires a registered point cloud of the target from different views, assuming no prior knowledge of the object, nor any of its properties. This work features a new set of metrics for grasp pose candidates evaluation, as well as exploring the impact of high object sampling on grasp success rates. In addition to gripper position sampling, we now perform orientation sampling about the x, y, and z-axes, hence the grasping algorithm no longer require object orientation estimation. Successful experiments have been conducted on a simple jaw gripper (Franka Panda gripper) as well as a complex, high Degree of Freedom (DoF) hand (Allegro hand) as a proof of its versatility. Higher grasp success rates of 76% and 85.5% respectively has been reported by real world experiments

Grasping Unknown Objects Based on Gripper Workspace Spheres

In this paper, we present a novel grasp planning algorithm for unknown objects given a registered point cloud of the target from different views. The proposed methodology requires no prior knowledge of the object, nor offline learning. In our approach, the gripper kinematic model is used to generate a point cloud of each finger workspace, which is then filled with spheres. At run-time, first the object is segmented, its major axis is computed, in a plane perpendicular to which, the main grasping action is constrained. The object is then uniformly sampled and scanned for various gripper poses that assure at least one object point is located in the workspace of each finger. In addition, collision checks with the object or the table are performed using computationally inexpensive gripper shape approximation. Our methodology is both time efficient (consumes less than 1.5 seconds in average) and versatile. Successful experiments have been conducted on a simple jaw gripper (Franka Panda gripper) as well as a complex, high Degree of Freedom (DoF) hand (Allegro hand)

Soft pneumatic grippers embedded with stretchable electroadhesion

Current soft pneumatic grippers cannot robustly grasp flat materials and flexible objects on curved surfaces without distorting them. Current electroadhesive grippers, on the other hand, are difficult to actively deform to complex shapes to pick up free-form surfaces or objects. An easy-to-implement PneuEA gripper is proposed by the integration of an electroadhesive gripper and a two-fingered soft pneumatic gripper. The electroadhesive gripper was fabricated by segmenting a soft conductive silicon sheet into a two-part electrode design and embedding it in a soft dielectric elastomer. The two-fingered soft pneumatic gripper was manufactured using a standard soft lithography approach. This novel integration has combined the benefits of both the electroadhesive and soft pneumatic grippers. As a result, the proposed PneuEA gripper was not only able to pick-and-place flat and flexible materials such as a porous cloth but also delicate objects such as a light bulb. By combining two soft touch sensors with the electroadhesive, an intelligent and shape-adaptive PneuEA material handling system has been developed. This work is expected to widen the applications of both soft gripper and electroadhesion technologies