Procedures for PET studies

The agitation studies for PET depolymerization were performed in the Atlas Launder-ometer. The Launder-ometer is a device for rotating closed containers in a thermostatically controlled water bath. The procedure used in these experiments was adapted from an American Association of Textile Chemists and Colorists (AATCC) standard test method. The 5% sodium hydroxide solution (250 mL) was preheated to 80°C in a 1-pint stainless steel jar. The catalysts were added in the following amounts in separate experiments TOMAC (0.04 g, 0.0001 mol) TOMAB (0.045 g, 0.0001 mol) and HTMAB (0.045 g, 0.0001 mol). The PET fiber specimens (1.98 g, 0.01 mol) were placed in the containers along with ten -in. stainless steel balls to aid in the agitation process. The jars were sealed in the Launder-ometer, whose bath was at the desired temperature (80°C). The machine was allowed to run for the allowed treatment times (i.e., 30, 60, 90, 150, and 240 min) at 42 rpm. Upon decanting, any residual fibers... 

Eq. (5) in conjunction with Eqs. (8) and (9) have, so far, provided adequate representation of experimental isotherms6 32, which are characterized by an initial con vex-upward portion but tend to become linear at high pressures. Values of K, K2 and s0 have been deduced by appropriate curve-fitting procedures for a wide variety of polymer-gas systems. Among the polymers involved in recent studies of this kind, one may cite polyethylene terephthalate (PET) l2 I4), polycarbonate (PC) 19 22,27), a polyimide l6,17), polymethyl and polyethyl methacrylates (PMMA and PEMA)l8), polyacrylonitrile (PAN)15), a copolyester 26), a polysulphone 23), polyphenylene oxide (PPO)25), polystyrene (PS) 27 28), polyvinyl acetate 29) and chloride 32) (PVAc and PVC), ethyl cellulose 24) (EC) and cellulose acetate (CA) 30,3I>. A considerable number of gases have been used as penetrants, notably He, Ar, N2, C02, S02 and light hydrocarbons. 

Many of the separation techniques we have described take hours to perform. Many interesting nuclei, such as the heavier actinides, the transactinides, or the light nuclei used in PET studies, have much shorter half-lives. Thus, we will briefly review the principles of rapid radiochemical separations (procedures that take seconds to minutes) and refer the reader to Henman and Trautman (1982), Meyer and Henry (1979), Schadel et al. (1988), and Trautman (1995) for details. 

Demertzis P G, Johansson F, Lievens C and Franz R, 1997, Studies on the development of a quick inertness test procedure for multi-use PET containers - sorption behaviour of bottle wall strips. Packaging Technology and Science 10,45-58. 

However, in the United States, the CMS uses these codes for classification of surgical, diagnostic, and therapeutic procedures. Along with CPT/HCPCS codes, Dx (ICD-9-CM) codes must be provided on the claim form for reimbursement. These codes are annually reviewed and updated. A few current representative Dx (ICD-9-CM) codes for the diagnosis of diseases by PET studies are given in Table 10.2. 

For many years, PET procedures were considered by the CMS as experimental and research-based and so were not reimbursed, although some private insurers did pay for the PET studies for very specific cases. Based on the approval of 82Rb-RbCl by the FDA in 1989 for myocardial perfusion studies, and after a thorough review of scientific literature on the outcome of the PET study, the CMS first approved reimbursement for PET myocardial perfusion scans using 82Rb-RbCl for both rest and pharmacological stress studies... 

An alternate method is described in (Nickles et al. 1993b). A Mo foil (0.1 mm thick) was used for irradiation and the radiotechnetium was extracted by an electrochemical etching procedure. With the obtained Tc-pertechnetate, Tc-teboroxime was prepared, which was used for the first preliminary human investigation with this " Tc-la-beled pharmaceutical (Nickles et al. 1993 b). Another PET study with Tc-2-methoxy isobutyl isonitrile was also reported (Stone et al. 1994). 

Before I was injected with carfentanil, we had carried out studies in rodents and baboons. The dose that I was to be given would be exceedingly small, but we thought it wise to have an anesthetist and an anesthesia machine present in case my breathing stopped. As it turned out, there was no effect on my breathing, but there was constriction of my pupils. We scheduled a second injection and PET imaging procedure for the next day in the nuclear medicine department. 

Choice of Silanes for SiOx Film Deposition. Plasma polymerization of silanes results in plasma polymer films which contain carbonaceous components such as Si-C and CH2-CH2 groups within SiOx networks. In order to form SiOx networks without the carbonaceous components, carbonaceous components should be excluded from the deposited SiOx films. Many researchers have followed a heating procedure for the elimination of the carbonaceous components from the deposited SiOx films but this procedure is not applicable to SiOx-deposited PET films because of poor thermal-resistance of the film. In this study, a silane that was suitable for the SiOx deposition with less carbonaceous component was investigated. Five silanes, TEOS, TrEOS, TMOS, DMDMOS, and TMS, which contained different C/Si atomic ratio of 8 to 4 and different bond structure (Si-O-C and Si-C bonds) between Si and C atoms, were used for the plasma polymerization. Table I compares file C/Si atomic ratio in the deposited SiOx films from the five silanes. The C/Si atom ratio in the deposited SiOx films, as shown in Table I, depends on the C/Si atomic ratio and the bond structure in the starting silanes Silanes with a small C/Si atom ratio deposit SiOx films with a low carbon content, and silanes with Si-O-C bonds also deposit SiOx films with a low carbon content. From this viewpoint, TMOS is preferable to TEOS, TrEOS, DMDMOS, and TMS as a silane for SiOx deposition with a less carbonaceous component, although TMOS is not yet a satisfactory material for the SiOx deposition. The SiOx film deposited from TMOS reveals a C/Si atom ratio of 1.5. 

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