Implant reference materials

Indeed, the National Institute for Standards and Technology (NIST) presently provides three traceable implant reference materials, these being Boron, Phosphorus, and Arsenic implanted into Silicon. Closely aligned are the implant reference materials available from the Evans Analytical Group (EAG), and so on. Other implant reference material combinations require custom fabrication and validation. 

The technique of Mossbauer spectroscopy is especially suited to chemical studies of implanted ions. The great amount of reference material allows in most cases rather detailed statements on the chemical bonding of an element implanted in compounds. The implantation dose necessary for Mossbauer spectra is not too high. That means that the lattice order is normally preserved. 

Silicone elastomers have a long history of use in the medical field. They have been applied to cannulas, catheters, drainage tubes, balloon catheters, finger and toe joints, pacemaker lead wire insulation, components of artificial heart valves, breast implants, intraocular lenses, contraceptive devices, burn dressings and a variety of associated medical devices. A silicone reference material has been made available by the National Institutes of Health to equate the blood compatibility of different surfaces for vascular applications. This material is available as a silica-free sheet. Contact the Artificial Heart Program, NHBLI, NIH, Bethesda, Md. for further information. 

Tung, M. S. and Sung, P Calcium Phosphate Type Reference Material Development, Preparation, and Characterization, Characterization and Performance of Calcium Phosphate Coatings for Implants, ASTM STP 1196, E. Horowitz and J. E. Pair, Eds., ASTM International, West Conshohocken, PA, 1994, pp. 99-110. 

As a specific isotope of a specific element is typically introdnced in ion implantation, quantification via Relation 5.5 provides the concentration of the respective isotopic. If the substrate of interest contains all of the isotopes of the element, and the overall concentration is required, then the RSF must be corrected for the respective isotopic abundance present in the reference material. 

Incorporation of signals fi om surface adsorbates into the derivation of implanted ion dose measurements. Note Airborne molecules readily adsorb onto both reference materials and substrates of interest. This also occurs within UHV chambers (see Section 4.2.1.1)... 

The RSF approach can, however, only be applied if matrix-matched reference materials exist. As this is rarely the case in nature, these have to be fabricated. Although a number of approaches exist, the most common relies on the implantation of the element of interest into some matrix. As for molecular signals, alternative solution chemistry approaches are required. In all cases, the reference material must be well characterized using other analytical techniques. The requirement of well-characterized matrix-matched reference materials represents... 

Despite these problems. WG2 currently has two items under development. Procedure for Certification of lon-lmplanted Reference Materials for Analysis of Semiconductor Wafers and Ion-Implanted Dosimetry Calibration by Surface Analytical Techniques. 

This chapter will focus on fundamental concepts related to surface modification of materials utilized within polymeric biocomposites for orthopedic applications. For this chapter, orthopedic applications are defined as medical indications or procedures that benefit from utilization of polymeric biocomposites and/or additional implanted therapeutic material to aid in bone regeneration at a localized site. The term surface modification refers to the physical attachment of molecules, predominantly silanes and/or polymers, to the surface of a solid-phase material. Polymeric biocomposites are a class of biomaterials that comprises a biocompatible bulk polymer and a particulated solid phase, often referred to as a binder and a filler, respectively. As there are vast combinations of polymers and solid materials that fit this definition, this chapter highlights solely those combinations that have been utilized for orthopedic applications, in either the acadenuc or the medical industry settings. 

These polymeric materials are fabricated to mimic the shape of natural bone, in a form referred to as a scaffolding. The scaffolding provides open spaces in which the body s osteoblasts can begin the regeneration of new hone. When regeneration is complete, the new bone can take over the structural chores temporarily performed by the bone implant. 

FIGURE 2 compares the room temperature PL data from Zn-implanted GaN samples annealed at 1150°C and 1250°C under 10 kbar N2 with an MOVPE-doped GaN Zn reference sample and the undoped GaN/sapphire starting material [8], The MOVPE Zn dopant concentration was designed to closely match the implantation profile to provide an accurate comparison of the relative Zn luminescence efficiencies. The spectra observed in all of the Zn-doped samples are similar, differing rally in intensity, which confirms the activation of the implanted Zn acceptors. The sample annealed at 1250°C shows intense Zn PL roughly an order of magnitude stronger than in the epitaxial GaN Zn reference sample... 

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