Permanent 125I-seed prostate brachytherapy: early prostate specific antigen value as a predictor of PSA bounce occurrence

<p>Abstract</p> <p>Purpose</p> <p>To evaluate predictive factors for PSA bounce after ¹²⁵I permanent seed prostate brachytherapy and identify criteria that distinguish between benign bounces and biochemical relapses.</p> <p>Materials and methods</p> <p>Men treated with exclusive permanent ¹²⁵I seed brachytherapy from November 1999, with at least a 36 months follow-up were included. Bounce was defined as an increase ≥ 0.2 ng/ml above the nadir, followed by a spontaneous return to the nadir. Biochemical failure (BF) was defined using the criteria of the Phoenix conference: nadir +2 ng/ml.</p> <p>Results</p> <p>198 men were included. After a median follow-up of 63.9 months, 21 patients experienced a BF, and 35.9% had at least one bounce which occurred after a median period of 17 months after implantation (4-50). Bounce amplitude was 0.6 ng/ml (0.2-5.1), and duration was 13.6 months (4.0-44.9). In 12.5%, bounce magnitude exceeded the threshold defining BF. Age at the time of treatment and high PSA level assessed at 6 weeks were significantly correlated with bounce but not with BF. Bounce patients had a higher BF free survival than the others (100% versus 92%, p = 0,007). In case of PSA increase, PSA doubling time and velocity were not significantly different between bounce and BF patients. Bounces occurred significantly earlier than relapses and than nadir + 0.2 ng/ml in BF patients (17 vs 27.8 months, p < 0.0001).</p> <p>Conclusion</p> <p>High PSA value assessed 6 weeks after brachytherapy and young age were significantly associated to a higher risk of bounces but not to BF. Long delays between brachytherapy and PSA increase are more indicative of BF.</p

Determination of Concentration Distributions of Gaseous and Solid Intermediate Reaction Products in a Combustion Chamber by a Water Cooled Sampling Probe

The multiphase combustion process of metallised solid fuel slabs has been investigated with a water cooled sampling probe system under ramjet relevant conditions concerning the air inlet temperature. The spatial distribution of concentrations of gaseous stable (intermediate) reaction products as well as the boronoxide content of the collected solid phase inside the combustor have been determined. The sampling probe system, the sampling procedure as well as the planar step combustor test facility are described. With the continuous monitoring of the pressure inside the tip of the probe the correct operating condition of the sampling system can be observed. Concentration profiles of major species obtained at several measuring cross sections of the step combustor are presented here

A Short Discussion on Performance, Safety and Environmental Aspects of Gel and Hybrid Rocket Propulsion Systems

Rocket systems, which are operated either with gel propellants or with hybrid propellant combinations, show combinations of safety and performance benefits which are advantageous in comparison to conventional liquid and solid rocket propulsion systems. To these advantages belong a reduced hazard potential, thrust variation capabilities up to shut-down and re-ignition, and simplified handling characteristics if suitable propellants or propellant combinations are used. This paper gives a short introduction into the technology of both propulsion system types, which both use advanced propellants and propellant combinations to realize these benefits. The hazard potential of these two propulsion systems can thus essentially be reduced to the hazard potential related to the used propellants or propellant combinations itself, which are in tanks or are lining the combustor, due to their systemic advantages

Generalized reynolds number for non-newtonian fluids

An extended version of the generalized Reynolds number was derived to characterize the duct flow of non-Newtonian gelled fluids of the Herschel-Bulkley-Extended (HBE) type. This number allows also estimating the transition from laminar to turbulent flow conditions. An experimental investigation was conducted with a capillary rheometer for several non-Newtonian gelled fluids to evaluate the introduced HBE-generalized Reynolds number Regen HBE. A good correlation between the experimental results and the theory could be found for laminar flow conditions. For one of the examined gelled fuels, the necessary high Reynolds numbers could be realized so that the transition from the laminar to the turbulent flow regime could be measured. Because of its general description, the HBE-generalized Reynolds number can also be applied to Newtonian liquids as well as to non-Newtonian fluids of the Herschel-Bulkley (HB), Ostwald-de-Waele (power-law, PL), and Bingham type

Status of Gel Propulsion in the Year 2010 with a Special View on the German Activities

Gel propellants are interesting candidates for rocket and ramjet propulsion systems. Due to their non-Newtonian flow behavior they offer the possibility to built throttleable engines with easy handling and storage capabilities. The current publication gives a very short description of the actual state of knowledge and technology development whereas a special focus will be given on the activities within the scope of the German Gel Technology Program. Furthermore a short overview about some existing and new proposals for applications of gel propulsion systems is given. Summarizing it can be said that up to now the understanding of basic processes as well as the knowledge about combustor and engine technology on gel propulsion has significantly improved, but there are still open gaps to close

Spray behavior of non-newtonian fluids: correlation between rheological measurements and droplets/threads formation

The formation of thread-like structures instead of droplets has been observed in recent studies on the injection of various gels and nonNewtonian fluids through a doublet impinging jet injector. In the present work, it has been studied if a correlation can be found between distinct fluid properties and thread formation. For this task, the tests have been conducted with different classes of fluids with various fluid properties. These classes are: Boger fluids, linear and crosslinked polymer solutions, and silica suspensions. The results show that a correlation exists between thread formation and the extensional behavior of the fluid, in particular, high values of the Trouton ratio. The characterization of the extensional behavior of fluids with a distinct yield stress has been conducted with a capillary rheometer, and the results obtained with this technique are compared to the spray behavior

Estimation of Flow Properties of Gelled Fuels with Regard to Propulsion Systems

Gelled fuels and propellants are shear-thinning non-Newtonian fluids. Their dependency of the shear viscosity from the shear rate can be described with sufficient accuracy by an extended version of the Herschel-Bulkley equation in the whole rocket and ramjet propulsion-relevant shear-rate range. Additionally to the analytically determined generalized Reynolds number for fluids, which follow the extended Herschel-Bulkley equation, a method for the estimation of critical Reynolds numbers (as a phenomenological approach) is presented. Both dimensionless numbers are useful for the characterization of the flow and partially also of the spray processes of gel fluids. The results show furthermore that both the shear-thinning property and the yield stress tend to stabilize the laminar flow and thus shift the critical Reynolds number to higher values when compared to Newtonian liquids