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Implant location

The release profile of total radiolabeled species affected by implant location follows practically a zero order of kinetics. [Pg.71]

The interaction of the host tissue with the polymer depends on the implantation site. For example, a pH sensitive suture that exhibits no degradation at a subcutaneous location may exhibit rapid degradation at an acidic location such as the stomach. A material may therefore demonstrate a toxic response at one implantation location but not at another. Similarly, the issue of patient diversity (age, gender, health status, physical condition, size, etc.) lends itself to distinctive device interactions specific to patient characteristics. [Pg.145]

Biologic factors — these are determined by the implant host (human, dog, hog, rabbit, sheep), and implant location (abdominal, dorsal, forearm) ... [Pg.741]

Toxicity of biomaterials is usually viewed at both cellular and systemic levels. Toxicity at the cellular level, also known as cytotoxicity, is often caused by direct chemical toxicity of biomaterials, inflammatory reactions, or immune responses to biomaterials. Excessive or severe cytotoxicity, inflammatory reactions, or immune responses may lead to the toxicity remote from the initial insult and affecting organs or organ systems, which is defined as systemic toxicity. It is important to emphasize that toxicity caused by biomaterials is usually dose dependent. For cytotoxicity or nonimmune systemic toxicity, a threshold below which the biomaterial reveals little toxicity may be carefully determined by in vitro and in vivo studies. However, for immune systemic toxicity, determination of such a threshold is extremely difficult because immune responses are individual-dependent and largely affected by properties, dosage, and implantation location of the biomaterials. Toxicity of nanomaterials will be further discussed in this chapter. [Pg.183]

Fig. 10.16. Nonoptimally resectable ovarian cancer. Multiple peritoneal implants (arrows) are demonstrated on the liver surfece and lesser sac. The latter is distended due to ascites. The implants located in the interlobar fissure (asterisk) and lesser sac (asterisk) are considered nonoptimally resectable... Fig. 10.16. Nonoptimally resectable ovarian cancer. Multiple peritoneal implants (arrows) are demonstrated on the liver surfece and lesser sac. The latter is distended due to ascites. The implants located in the interlobar fissure (asterisk) and lesser sac (asterisk) are considered nonoptimally resectable...
At this point in the design process there may be more than one proposed implant location. [Pg.1514]

It used to be relatively easy to tell a pacemaker from an ICD because of the difference in generator size and implant location. Today it isn t so easy. The generators are similar in size, and both kinds of devices are implanted under the skin of the patient s chest Whafs more, a single device may perform multiple functions. [Pg.194]

The difference in rates of release of BCNU from wafers produced by the trituration or solution methods is also seen in vivo (11,14), as is shown in Fig. 6. Wafers of PCPP-SA 20 80 were prepared by either the solution or trituration methods, as described above, and were implanted into the brains of rabbits. The animals were sacrificed at various times after implantation and the brains were removed, fixed, and processed for quantitative autoradiography. To quantitate the percentage of the brain exposed to BCNU released from these wafers, the following calculation was performed. The percentage of the brain in which the radioactivity from the tritiated BCNU released from the wafers exceeded the background counts by at least two standard deviation units was plotted as a function of time following implantation in Fig. 6. A control set of rabbits had a solution of BCNU injected directly into the same location in the... [Pg.52]

The plasma potential is the maximum value with which ions can be accelerated from the edge of the sheath towards the substrate, located at the grounded electrode. This may cause ion bombardment, which may induce ion-surface interactions such as enhancement of adatom diffusion, displacement of surface atoms, trapping or sticking of incident ions, sputtering, and implantation see Section 1.6.2.1. [Pg.29]

This diffusion chamber was modified to provide a uniform flow from two channels at the entrance, one for the filtered room air and the other for the gas from the radon chamber. This modified mobility analyzer is schematically shown in Figure 2. The pressure heads are adjusted so that the gas velocities, v, are the same in both channels. An adjustable vertical electric field, E, is provided through the analyzer so that charged particles are drawn toward the detector located at x cm from the entrance. With the known distance, d, between the radon-laden gas channel and the detector implanted plate, the mobility can then be determined from... [Pg.363]

In Chapter 8, Stavola and Pearton discuss the local vibrational modes of complexes in Si that contain hydrogen or deuterium. They also show how one can use applied stress and polarized light to determine the symmetry of the defects. In the case of the B-H complex, the bond-center location of H is confirmed by vibrational and other measurements, although there are some remaining questions on the stress dependence of the Raman spectrum. The motion of H in different acceptor-H complexes is discussed for the Be-H complex, the H can tunnel between bond-center sites, while for B-H the H must overcome a 0.2 eV barrier to move between equivalent sites about the B. In the case of the H-donor complexes, instead of bonding directly to the donor, H is in the antibonding site beyond the Si atom nearest to the donor. The main experimental evidence for this is that nearly the same vibrational frequency is obtained for the different donor atoms. There is also a discussion of the vibrational modes of H tied to crystal defects such as those introduced by implantation. The relationship of the experimental results to recent theoretical studies is discussed throughout. [Pg.22]

Applications of Lattice Location a. The Site Occupied by Implanted Hydrogen... [Pg.220]

Extensive channeling measurements on 2H implanted into silicon have been published by Bech Nielsen (1988). These measurements also use the 3He-induced nuclear reaction in conjunction with extensive modeling using the statistical equilibrium model already described. The 2H implants were done at 30 K, and lattice location of the 2H was done as a function of annealing. [Pg.220]

Fig. 20. SIMS profiles of total deuterium density across p-n junctions formed by implanting phosphorus into a (100) silicon water uniformly doped with 1 x 1017 boron atoms per cm3 for various times of deuteration at 150°C (Johnson, 1986a). The phosphorus profile is also shown and serves to locate the pre-deuteration depth of the junction at 0.5 Deuteration was from downstream gases from a plasma discharge (Johnson and Moyer, 1985). Fig. 20. SIMS profiles of total deuterium density across p-n junctions formed by implanting phosphorus into a (100) silicon water uniformly doped with 1 x 1017 boron atoms per cm3 for various times of deuteration at 150°C (Johnson, 1986a). The phosphorus profile is also shown and serves to locate the pre-deuteration depth of the junction at 0.5 Deuteration was from downstream gases from a plasma discharge (Johnson and Moyer, 1985).
The Safe Medical Devices Act requires reporting of medical devices that probably caused the death, serious filness, or injury of a patient. Postmarket surveillance on permanently implanted devices required with methods for tracing and locating patients depending on such devices. FDA is authorized to recall device product. [Pg.495]

One of the most commonly used medical devices is the stent, (Fig. 21.1), small metallic structures that are expanded in blood vessels, functioning to maintain the patency (freedom from obstruction) of the vessel in which it is placed. Although the first use of stents was in vasculature (blood vessel systems), more recent applications include, for example, implantation between two vertebrae to increase the rigidity of the spine. A typical vascular stent is placed in its anatomical location and then either plastically deformed/expanded (stainless steel) or allowed to expand to a predetermined size, as a consequence of shape memory (nitinol). [Pg.346]


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See also in sourсe #XX -- [ Pg.324 ]




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