Performance of a stationary vertical axis vane type rotor tested in a wind tunnel
This paper reports the performance of an equally spaced vertical axis vane type rotor tested in a wind tunnel. The aerodynamic characteristics i.e. torque coefficient, drag coefficient etc. of a stationary vane type rotor have been studied in this research work by measuring the pressure distribution on the blade surfaces at various rotor angles. The experimental investigation was performed on four bladed vertical axis vane type rotor in a uniform flow jet produced by an open circuit wind tunnel. It has been observed that the static torque varies at different rotor angles. Total static torque coefficient at different rotor angles curve repeats from 0° to 80°, 90° to 170°, 180° to 260° and 270° to 350° angle of rotation. A quasi-steady approach was applied for the prediction of dynamic performance of the rotor using the static drag and torque coefficients. This method results in a fair agreement with the measured power coefficient.
The Effects of a Deflecting Plate and Rotor End Plates on Performances of Savonius-type Wind Turbine
The effects of the shape of rotor end plates on rotor performances have been investigated empirically by using five kinds of the Savonius rotors. The optimum shape of the end plate has been found from experimental results, and it has been revealed that the contribution of the lift force to the rotor power is considerably large. Then, by using a deflecting plate placed in front of the rotor, it has been attempted to improve the performances of the Savonius-type wind turbine. By the use of the deflecting plate, the power has been increased about 24 %. It has been also proved that the deflecting plate can be used as a speed control device or a protection device of the Savonius-type wind turbine.
A functional comparison of human Fc-receptor-bearing lymphocytes active in natural cytotoxicity and antibody-dependent cellular cytotoxicity.
Natural (or “spontaneous”) cytotoxicity against the K-562 myeloid cell line and antibody-dependent cellular cytotoxicity (ADCC) against sensitized Chang liver cells were monitored simultaneously in a 4 hr 51 Cr release assay, using the same preparations of normal human peripheral blood lymphocytes as effector cells. Both types of cytotoxic activity were expressed by lymphocytes bearing receptors for sheep erythrocytes and for the Fc portion of IgG. Up to 80% of the total natural killer (NK) cell and K cell (ADCC) activities were recovered in E-rosette pellets separated under optimal conditions. Since the ability to form rosettes with sheep erythrocytes is primarily a marker for human T cells, it seems likely that both NK and K cells are in the T cell lineage. Further, both NK and K cell cytolytic activities were severely depressed after brief exposure of lymphocyte suspensions or rosette pellets to ammonium chloride solutions. Both activities returned to normal values after 24-hr incubation at 24°C. Such sensitivity of human lymphocytes to ammonium chloride solutions may explain why other investigators have failed to observe NK or ADCC activity by E-RFC. When lymphocytes bearing Fc receptors were adsorbed onto plastic surfaces coated with a monolayer of immobilized antigen-antibody complexes made up of TNP and rabbit anti-TNP serum, both NK and ADCC activities were simultaneously depleted. Such depletion was completely blocked when Staphylococcal protein A, which binds selectively to the Fc portion of IgG, was incubated on the antigen-antibody monolayers before adding the lymphocytes. This confirmed that both NK and ADCC activities were mediated by effector lymphocytes bearing Fc receptors. When protein A at concentrations ranging from 0.01 to 100 µg/ml was added to the 51 Cr release assays, ADCC was significantly inhibited, presumably due to binding of protein A to available Fc sites of the sensitizing antibody. However, protein A had no effect on NK reactivity at any of the concentrations tested. When lymphocytes were treated for 30 min at 37°C with purified trypsin or α-chymotrypsin at concentrations from 0.01 to 10 mg/ml, NK activity was significantly inhibited whereas ADCC was unaffected. Other enzymes depressed (pronase, subtilisin) had no effect except at high concentrations (lipase), or stimulated (neuraminidase) both NK and K cell activity similarly, and therefore failed to distinguish between the effector cell types. Thus, our data indicate that effector cells in NK and ADCC are in overlapping, if not identical, subpopulations of Fc receptor-bearing lymphocytes of probable T cell lineage. The cytolytic mechanisms in NK and ADCC appear to be distinct, since we have been unable to find evidence for an “arming” antibody involved in this NK system.