Development of tailorable advanced blanket insulation for advanced space transportation systems

Two items of Tailorable Advanced Blanket Insulation (TABI) for Advanced Space Transportation Systems were produced. The first consisted of flat panels made from integrally woven, 3-D fluted core having parallel fabric faces and connecting ribs of Nicalon silicon carbide yarns. The triangular cross section of the flutes were filled with mandrels of processed Q-Fiber Felt. Forty panels were prepared with only minimal problems, mostly resulting from the unavailability of insulation with the proper density. Rigidizing the fluted fabric prior to inserting the insulation reduced the production time. The procedures for producing the fabric, insulation mandrels, and TABI panels are described. The second item was an effort to determine the feasibility of producing contoured TABI shapes from gores cut from flat, insulated fluted core panels. Two gores of integrally woven fluted core and single ply fabric (ICAS) were insulated and joined into a large spherical shape employing a tadpole insulator at the mating edges. The fluted core segment of each ICAS consisted of an Astroquartz face fabric and Nicalon face and rib fabrics, while the single ply fabric segment was Nicalon. Further development will be required. The success of fabricating this assembly indicates that this concept may be feasible for certain types of space insulation requirements. The procedures developed for weaving the ICAS, joining the gores, and coating certain areas of the fabrics are presented

Tailorable advanced blanket insulation using aluminoborosilicate and alumina batting

Two types of Tailorable Advanced Blanket Insulation (TABI) flat panels for Advanced Space Transportation Systems were produced. Both types consisted of integrally woven, 3-D fluted core having parallel faces and connecting ribs of Nicalon yarns. The triangular cross section flutes of one type was filled with mandrels of processed Ultrafiber (aluminoborosilicate) stitchbonded Nextel 440 fibrous felt, and the second type wall filled with Saffil alumina fibrous felt insulation. Weaving problems were minimal. Insertion of the fragile insulation mandrels into the fabric flutes was improved by using a special insertion tool. An attempt was made to weave fluted core fabrics from Nextel 440 yarns but was unsuccessful because of the yarn's fragility. A small sample was eventually produced by an unorthodox weaving process and then filled with Saffil insulation. The procedures for setting up and weaving the fabrics and preparing and inserting insulation mandrels are discussed. Characterizations of the panels produced are also presented

AKT1 and AKT2 maintain hematopoietic stem cell function by regulating reactive oxygen species

Although AKT is essential for multiple cellular functions, the role of this kinase family in hematopoietic stem cells (HSCs) is unknown. Thus, we analyzed HSC function in mice deficient in the 2 isoforms most highly expressed in the hematopoietic compartment, AKT1 and AKT2. Although loss of either isoform had only a minimal effect on HSC function, AKT1/2 double-deficient HSCs competed poorly against wild-type cells in the development of myeloid and lymphoid cells in in vivo reconstitution assays. Serial transplantations revealed an essential role for AKT1 and AKT2 in the maintenance of long-term HSCs (LT-HSCs). AKT1/2 double-deficient LT-HSCs were found to persist in the G0 phase of the cell cycle, suggesting that the long-term functional defects are caused by increased quiescence. Furthermore, we found that the intracellular content of reactive oxygen species (ROS) is dependent on AKT because double-deficient HSCs demonstrate decreased ROS. The importance of maintaining ROS for HSC differentiation was shown by a rescue of the differentiation defect after pharmacologically increasing ROS levels in double-deficient HSCs. These data implicate AKT1 and AKT2 as critical regulators of LT-HSC function and suggest that defective ROS homeostasis may contribute to failed hematopoiesis