Accelerated fractionation

Trott KR, Kummermehr J. What is known about tumour proliferation rates to choose between accelerated fractionation or hyperfractionation Radiother Oncol 1985 3(1) 1-9. 

Accelerated fractionated therapy with concomitant boost (Table 1). 

Fu KK, Pajak TF, Trotti A, et al. A Radiation Therapy Oncology Group (RTOG) phase III randomized study to compare hyperfractionation and two variants of accelerated fractionation to standard fractionation radiotherapy for head and neck squamous cell carcinomas first report of RTOG 9003. lnt J Radiat Oncol Biol Phys 2000 48 7-16. 

Other trials attempted to improve the results of sequential chemoradiation by using newer ChT agents and/or intensifying the RT component by the use of accelerated fractionation, based on the success of the British CHART regimen. A phase II trial of paclitaxel and carboplatin followed by hyperfractionated accelerated radiation therapy (HART) to... 

In patients with squamous cell carcinomas of the head and neck accelerated radiotherapy with carbogen and nicotinamide 6 g/day (ARCON) was carried out to determine the feasibility and the adverse effects of this therapeutic approach (31). Accelerated fractionation was combined with carbogen (n = 11), daily nicotinamide (n — 10), or both (n = 17). There were no significant differences in local adverse effects in the three groups. Systemic adverse effects took the form of nausea or vomiting. The authors concluded that in future ARCON trials a lower dose of nicotinamide will be needed to reduce severe upper gastrointestinal toxicity. 

Fedotov, P. S., Zavarzina, A. G., Spivakov, B. Ya., Wermrich, R., Mattusch, J., Titze, K de P. C., and Demin, V. V. (2002). Accelerated fractionation of heavy metals in contaminated soils and sediments using rotating coiled columns. J. Environ. Monit. 4, 318-324. 

Regine WF, Scott C, Murray K, et al Neurocognitive outcome in brain metastases patients treated with accelerated-fractionation vs accelerated-hyperfractioned radiotherapy an analysis from Radiation Therapy Oncology Group Study 91-04. Int J Radiat Oncol Biol Phys 51 711-717, 2001... 

Fu et al. 2000 Stage 11 IV head and neck tumors Accelerated fractionation with concomitant boost, 72 Gy 5-Year locoregional control 50%... 

For liquid-liquid separations, the basic Newton-Raphson iteration for a is converged for equilibrium ratios (K ) determined at the previous composition estimate. (It helps, and costs very little, to converge this iteration quite tightly.) Then, using new compositions from this converged inner iteration loop, new values for equilibrium ratios are obtained. This procedure is applied directly for the first three iterations of composition. If convergence has not occurred after three iterations, the mole fractions of all components in both phases are accelerated linearly with the deviation function... 

A catalyst is a material that accelerates a reaction rate towards thennodynamic equilibrium conversion without itself being consumed in the reaction. Reactions occur on catalysts at particular sites, called active sites , which may have different electronic and geometric structures than neighbouring sites. Catalytic reactions are at the heart of many chemical industries, and account for a large fraction of worldwide chemical production. Research into fiindamental aspects of catalytic reactions has a strong economic motivating factor a better understanding of the catalytic process... 

B = outlet diameter or width, g = acceleration owing to gravity, m = 1 for circular opening and 0 for slotted opening, and 0 = hopper angle (measured from vertical) in degrees. A modification of this equation takes particle size into account. This modification is only important if the particle size is a significant fraction of the outlet size (8). 

Droplet Dispersion. The primary feature of the dispersed flow regime is that the spray contains generally spherical droplets. In most practical sprays, the volume fraction of the Hquid droplets in the dispersed region is relatively small compared with the continuous gas phase. Depending on the gas-phase conditions, Hquid droplets can encounter acceleration, deceleration, coUision, coalescence, evaporation, and secondary breakup during thein evolution. Through droplet and gas-phase interaction, turbulence plays a significant role in the redistribution of droplets and spray characteristics. 

The same procedure may be applied in principle to design of forced-recirculation reboilers with shell-side vapor generation. Little is known about two-phase flow on the shell side, out a reasonable estimate of the fric tion pressure drop can be made from the data of Diehl and Unruh [Pet Refiner, 36(10), 147 (1957) 37(10), 124 (1958)]. No void-fraction data are available to permit accurate estimation of the hydrostatic or acceleration terms. Tnese may be roughly estimated by assuming homogeneous flow. 

---