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The enzyme glutamate dehydrogenase (GDH) from Escherichia coli is a hexameric protein. The stability of this enzyme was increased in the presence of Li + in concentrations ranging from 1 to 10mM, 1M of sodium phosphate, or 1M ammonium sulfate. A very significant dependence of the enzyme stability on protein concentration was found, suggesting that subunit dissociation could be the first step...
Over the last four decades of human spaceflight, the capabilities and complexity of manned spacecraft systems have increased significantly to meet the evolving requirements of the mission. The management of the vehicle systems, both by the crew on-board and the operators in the mission control center (MCC), has also evolved to take advantage of new capabilities, or simply to react to the features...
Achieving a sustainable exploration program requires development of a foundation of knowledge, validated technologies, and tools that support safe/reliable, affordable, effective, and flexible systems. Furthermore, the exploration program requires new paradigms in program execution and mission operations to meet both technical and budgetary challenges of space exploration missions. New technologies...
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