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An immuno-nephelometric me- thod, in a continuous flow system for the determination of plasma fibrinogen is described. The method is specific, rapid (60 determinations per hour), requires only 0.03 ml of plasma and compares favourably (r = 0.923 ± 0.038) with Leclerc’s colorimetric method.

Lifting and Blowoff of Flames from Short Cylindrical Burner Ports Sir: Reference is made to Channing W. Wilson's paper, "Lifting and Blowoff of Flames from Short Cylindrical Burner Ports," Ind. Eng. Chem., 44, 2937Chem., 44, (1952]. Although the experimental data apparently correlate very well, there are several inconsistencies in the theoretical treatment.Equation 1 is valid for either laminar or turbulent flow, but the resistance or frictional coefficient, , in Equation 1 is twice the value of used in Equation 2. Since Equation 2 is used m the development of the final correlation, Equation 2 should be written in order to be consistent with the defined in the equations forCases A, B, and C on page 2941.

The work described hereafter has been performed in the general framework of a pre-industrial PVD reactor development. This device is devoted to the online coating of ceramic fibers for aerospace industries and, to achieve this task, the fiber passes axially through an hollow cylindrical target which is sputtered by the confined plasma.This unusual geometry has been chosen to maximize the flux of sputtered atoms on the fiber although the ratio between facing surfaces remains very low and to produce a columnar plasma which should ideally stand close to the inner surface of the target. It should also be noted that the ratio between the length and the radius of the confining target is high (-30), and can be suspected to generate instabilities.The plasma is at the moment obtained with argon gas and is sustained by a electron gun which provides it a feeding DC current. The electromagnetic configuration of the reactor chamber is initially defined by the electron gun potential located at the top of the cylindrical target, by the anode potential located at the bottom and by the potential of the target itself. Moreover, the running fiber can be polarized if necessary. On the other hand a mainly longitudinal magnetic field is supposed to play the double role of magnetic bottle (the field closes up near both the gun and the anode) and ionization booster (a magnetron effect should occur in the sheath).The key-feature experimentally observed on a steady fiber is the following : the coating is longitudinally inhomogeneous and shows two sharp maximums located at the edges of the target whereas its center is characterized by a very tiny sputtered film. This reproducible experimental evidence can hardly be linked to standard probe measurements which seem to reveal an historydependent plasma configuration. Moreover, probe measurements cannot be performed in the same conditions that the coating and are not necessarily reliable.We recently started Monte Carlo simulations to reproduce, understand and fix this phenomenon. First computations show that electrons are accelerated from the gun, following the magnetic field lines (as it is classically expected) but loose their energy in the first collisions which occur at the top of the target. Then, they are probably not able to recover this lost energy in the constant plasma potential. Further numerical results should confirm this hypothesis. In this case, post-accelerating strategies will be implemented to enhance the sputtering and the coating processes. 160