Some factors affecting transformation of Aspergillus nidulans - Problems and progress

Some factors affecting transformation of Aspergillus nidulans - Problems and progress

Relationships between pyrimidine metabolism and sensitivity to alkylating agents in Aspergillus nidulans.

Relationships between pyrimidine metabolism and sensitivity to alkylating agents in Aspergillus nidulans

Some factors affecting transformation of Aspergillus nidulans - Problems and progress.

Some factors affecting transformation of Aspergillus nidulans - Problems and progress

A sodium fluoride sensitive mutant of Aspergillus nidulans

Fluoride is a widely spread naturally occurring substance in many foods and is used extensively for industrial purposes. The addition of fluoride to drinking water has been assumed to be safe. However, a number of studies have indicated that sodium fluoride is both genotoxic and cytotoxic to mammalian cells (Tsutsui et al. 1984 Mut. Res. 139:193-198). There is conflicting evidence suggesting that NaF is not genotoxic (Kram et al. 1978 Mut. Res. 57:51-55; Martin et al. 1979 Mut. Res. 66:159-167; Li et al. 1987 Mut. Res. 192:191-202) and can suppress the activity of polyfunctional alkylating agents (Obe and Slacik-Erben 1973 Mut. Res. 18:369-371)

Ke models: Theoretical dynamic subsystems of longitudinal web strain

Efficient design and optimization of many production processes often require models which predict transient and steady state web strains. To date, much attention has been given to modeling web strains much less than unity. Considerably less attention however, has been given to modeling strains of relatively lower modulus materials. A particular related challenge often involves selection of dancers vs. load cells as feedback devices in tension control systems.This paper explores derivations of theoretical "Ke" models as primitive functions of roller motions. At a fundamental level, simple linear and nonlinear differential equations exist for each strain component or "subsystem" independent of others. Combinations can determine total strains in web spans including those at inputs and outputs of dancer rollers and within festoons. Validity is retained at any value of strain including zero and negative values (compression). The author demonstrates that mathematical equations of high web strains instead of becoming unwieldy, can be applied with accuracy and with a large degree of natural elegance. Applied classical control theory allows users a natural intuition when interpreting results which are primarily outputs of computer simulations.The "free web span" has been extensively studied within the web handling community and is again examined here as a 1st section of web under any dynamic strain feeding into a 2nd section of web between two driven rollers. A free web span Ke based model is compared to a first order approximate model of the same physical system while applying step changes to roller velocities. Both models are compared as final values of strain approach extremely high values toward infinity. Using Ke models, all strain-time trajectories in the free web span as a result of step changes to roller velocities are shown to be sections of an S-shaped curve designated "The Universal Strain Time Curve". The output of the first order approximate model, when plotted on the Universal Strain Time Curve (USTC), reveals that the first order approximate model may often be applied with acceptable results for strains from 0 through 25%. Finally, an example model of a tension control system with load cell feedback demonstrates how consecutively higher order subsystems may be included as elements of a Ke Subsystem Library.A practical and intuitive method of modeling web strains of any value has been developed here and may be applied by scientists and engineers having a basic knowledge of classical control system theory. With relatively accurate input data, effects on strain resulting from various roller inertias, web span lengths, dancers vs. load cells, and many other design decisions can be simulated. For both high and low modulus materials, Ke models provide a high degree of accuracy when simulating web strains during process design and optimization. This research is applicable to a broad spectrum of webs from thin plastics to paper, textiles, flat metals, wires, films, belts, foils, strips, threads, fabrics, and composites which are manufactured in rolling processes. The academic derivation process which has been applied also reinforces a useful framework to solve similar scientific problems

Space shuttle abort separation pressure investigation. Volume 2, Part B: Orbiter data at Mach 5

For abstract, see

A sodium fluoride sensitive mutant of Aspergillus nidulans

Fluoride is a widely spread naturally occurring substance in many foods and is used extensively for industrial purposes. The addition of fluoride to drinking water has been assumed to be safe. However, a number of studies have indicated that sodium fluoride is both genotoxic and cytotoxic to mammalian cells (Tsutsui et al. 1984 Mut. Res. 139:193-198). There is conflicting evidence suggesting that NaF is not genotoxic (Kram et al. 1978 Mut. Res. 57:51-55; Martin et al. 1979 Mut. Res. 66:159-167; Li et al. 1987 Mut. Res. 192:191-202) and can suppress the activity of polyfunctional alkylating agents (Obe and Slacik-Erben 1973 Mut. Res. 18:369-371)

Space shuttle abort separation pressure investigation. Volume 6: Orbiter data at Mach 2

For abstract, see

Investigation of the McDonnell-Douglas orbiter and booster shuttle models in proximity at Mach numbers 2.0 to 6.0. Volume 7: Proximity data at Mach 4 and 6, interference free and launch vehicle data

Aerodynamic data obtained from a space shuttle abort stage separation wind tunnel test are presented. The .00556 scale models of the orbiter and booster configuration were tested in close proximity using dual balances during the time period of April 21 to April 27 1971. Data were obtained for both booster and orbiter over an angle of attack range from -10 to 10 deg for zero degree sideslip angle. The models were tested at several relative incidence angles and separation distances and power conditions. Plug nozzles utilizing air were used to simulate booster and orbiter plumes at various altitudes along a nominal ascent trajectory. Powered conditions were 100, 50, 25 and 0 percent of full power for the orbiter and 100, 50 and 0 percent of full power for the booster. Pitch control effectiveness data were obtained for both booster and orbiter with power on and off. In addition, launch vehicle data with and without booster power were obtained utilizing a single balance in the booster model. Data were also obtained with the booster canard off in close proximity and for the launch configuration

Space shuttle abort separation pressure investigation. Volume 1, Part B: Booster data at Mach 5

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