Modelling of a Regenerative Liquid Propellant Gun

In the development of liquid propellant guns (LPG), there are numerous interdependent parameters which affect the performance of the gun. There are some difficulties in arriving at the dimensions of its various components. To help in this task, computer simulation was undertaken to predict the performance of a conceptual gun. This is a sensitivity study aimed at exploring the relationship between the interdependent parameters. The parameters which have a direct bearing on the performance of the gun, like areas of cross-section of vents, differential piston dimensions liquid propellant mass, and the combustion and reservoir chamber dimensions have been studied. The expected pressures and other parameters could be studied with the help of this model is thus helpful in the optimization of the design of LPGs

Modelling and Simulation of a Railgun powered by a Capacitor Bank

A railgun powered by a capacitor bank was developed to launch hypervelocity projectiles. The efficiency of the gun to a large extent will determine its feasibility for weapon applications. A simulation code was developed to predict the performance of the railgun. The railgun has been modelled as a time-varying impedance to determine the currents and the voltages from the power source. In the railgun circuit the currents and the voltages are of the order of hundreds of kiloamperes. Even very low impedances of the order of milli-ohm and micro-henry are substantial sources of energy losses. The measured and simulation currents at peak values agree with in 10%, validating the model. The simulation code accurately predicts the energy distribution in the system. Maximization of the projectile energy leads to improved and efficient designs. The simulation also leads to the optimized launcher pressure and payload velocity

Lymphokine-activated killer-cell function of lymphocytes from peripheral blood, regional lymph nodes and tumor tissues of patients with oral cancer

Lymphokine-activated killer (LAK) cells, generated from peripheral blood lymphocytes (PBL) from patients with oral cancer or oral leukoplakia and from healthy donors showed comparable lysis of 6 target tumor cell lines, including 3 derived from head and neck and oral cancers. The tumor burden of the host did not appear to influence the systemic LAK activity. LAK activity of lymphocytes infiltrating the tumor tissues (TIL) was also comparable to that of the PBL. Both TIL and PBL showed a parallel increase in proportion of HNK-I++ and CD-25+ CELLS upon activation with IL-2. The lymph-node lymphocytes (LNL) from metastatic (met) and non-metastatic (non-met) draining lymph nodes, however, showed reduced LAK activity and an increase in CD8 CELLS, in addition to CD25+ and HNK-I+ cells, when cultured with IL-2. When IL-2-activated LNL were co-cultured with autologous PBL during IL-2 activation of the latter, a strong suppressive effect was exerted by LNL In contrast, IL-2-activated PBL did not suppress autologous LAK generation in spite of an increase in CD8+ cells seen after activation with IL-2. Frequency distribution of LAK precursors was significantly lower in LNL than in PBL from oral cancer patients. LAK precursor frequency in TIL was comparable to that of PBL. The results show that, in oral cancer, regional lymph nodes may not have adequate IL-2-inducible cytotoxic potential, due to a reduced number of LAK progenitors and possible activation of suppressor cells. Alternatively, TIL can be a potential source for LAK cell function

Derivative microspectrophotometry of single cells in vivo

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Natural killer and lymphokine-activated killer cell-mediated cytotoxicity in patients with oral cancer

Peripheral blood lymphocytes (PBL) from untreated and treated oral cancer patients, lymph node lymphocytes (LNL) from metastatic (met) and nonmetastatic (non-met) lymph nodes, and tumour infiltrating lymphocytes (TIL) were tested for natural killer (NK) and lymphokine activated killer (LAK) cell cytotoxicity using appropriate targets in a short-term chromium release assay. The results showed that while both NK and LAK functions of PBL from oral cancer patients were comparable to those of normal healthy donors, the NK activity of metastatic and nonmetastatic LNL and TIL was highly compromised. On the other hand, potent LAK activity could be generated from all three lymphoid populations. Individual patients showing low NK activity displayed good LAK cytotoxicity, indicating that endogenous cells with low NK potential have adequate ability to respond to interleukin 2 (IL-2). LAK activity tested on autologous tumour targets revealed that TIL were the best source of LAK cells, followed by PBL and LNL