A digital computer simulation and study of a direct-energy-transfer power-conditioning system

A digital computer simulation technique, which can be used to study such composite power-conditioning systems, was applied to a spacecraft direct-energy-transfer power-processing system. The results obtained duplicate actual system performance with considerable accuracy. The validity of the approach and its usefulness in studying various aspects of system performance such as steady-state characteristics and transient responses to severely varying operating conditions are demonstrated experimentally

The variable polarity plasma arc welding process: Its application to the Space Shuttle external tank

The technical history of the variable polarity plasma arc (VPPA) welding process being introduced as a partial replacement for the gas shielded tungsten arc process in assembly welding of the space shuttle external tank is described. Interim results of the weld strength qualification studies, and plans for further work on the implementation of the VPPA process are included

KONSTRUKCIJA I MEHANIČKA CJELOVITOST BUŠOTINA ZA UTISKIVANJE CO2

Geologic Sequestration (GS) is part of a process known as “carbon capture and storage (CCS)” and represents the process of injecting CO2, into deep subsurface rock formations for long-term storage. For injecting of CO2 existing wells are used as well as new drilled wells. A well represents the most likely route for leakage of CO2 from geologic carbon sequestration. Maintaining mechanical integrity helps prevent the well and wellbore from becoming conduits for CO2 migration out of the injection zone. The typical components of a CO2 injection well are casing, tubing, cement, and packer. These components are relevant for maintaining mechanical integrity and ensuring CO2 does not migrate upwards from the injection zone into underground source of drinking water (USDW); therefore helping to ensure zonal isolation of the injected carbon dioxide. In order to have the safe underground storage of CO2 well integrity considerations should be present during all phases of well life including design phase, drilling, completion, injection, workover (service) and abandonment. The paper describes well design, well integrity and mechanical integrity tests (MITs) as a means of measuring the adequacy of the construction of the injection well and as a way to detect problems within the well system.Geološko skladištenje (GS) kao dio procesa “kaptiranje i skladištenje ugljičnog dioksida (CS)” predstavlja proces utiskivanja CO2 u duboko zaliježuće stijene radi trajnog skladištenja. U tu svrhu koriste se postojeće bušotine, ali se izrađuju i nove bušotine. Bušotina predstavlja najvjerojatniji put za migraciju CO2 iz stijena u kojima je on uskladišten. Održavanjem mehaničkog integriteta bušotine onemogućava se da bušotina i njen prstenasti prostor postanu putovi migracije CO2 iz utisne zone prema površini. Osnovne komponente bušotine za utiskivanje CO2 su: kolona zaštitnih cijevi, tubing, cementni kamen i paker. Ove komponente su bitne za održavanje mehaničkog integriteta i sprječavanje vertikalne migracije CO2 iz utisne zone u stijene koje sadrže pitku vodu (USDW) jer pomažu da se izolira zona (naslage stijena) u koju je ugljični dioksid utisnut. Radi postizanja sigurnog uskladištenja CO2 u podzemlju, integritet bušotine treba sagledati tijekom svih faza u radnom vijeku bušotine od planiranja, preko bušenja, opremanja, utiskivanja, održavanja (remonta) sve do trajnog napuštanja bušotine. U radu se opisuju konstrukcija utisne bušotine, cjelovitost bušotine te navode testovi mehaničkog integriteta (MITs) kojima se određuje da li je primijenjena odgovarajuća konstrukcija utisne bušotine i otkrivaju problemi unutar kanala bušotine

Phosphofructokinase 1 Glycosylation Regulates Cell Growth and Metabolism

Cancer cells must satisfy the metabolic demands of rapid cell growth within a continually changing microenvironment. We demonstrated that the dynamic posttranslational modification of proteins by O-linked β-N-acetylglucosamine (O-GlcNAcylation) is a key metabolic regulator of glucose metabolism. O-GlcNAcylation was induced at serine 529 of phosphofructokinase 1 (PFK1) in response to hypoxia. Glycosylation inhibited PFK1 activity and redirected glucose flux through the pentose phosphate pathway, thereby conferring a selective growth advantage on cancer cells. Blocking glycosylation of PFK1 at serine 529 reduced cancer cell proliferation in vitro and impaired tumor formation in vivo. These studies reveal a previously uncharacterized mechanism for the regulation of metabolic pathways in cancer and a possible target for therapeutic intervention

Sulfated glycans engage the Ang–Tie pathway to regulate vascular development

The angiopoietin (Ang)–Tie pathway is essential for the proper maturation and remodeling of the vasculature. Despite its importance in disease, the mechanisms that control signal transduction through this pathway are poorly understood. Here, we demonstrate that heparan sulfate glycosaminoglycans (HS GAGs) regulate Ang–Tie signaling through direct interactions with both Ang ligands and Tie1 receptors. HS GAGs formed ternary complexes with Ang1 or Ang4 and Tie2 receptors, resulting in potentiation of endothelial survival signaling. In addition, HS GAGs served as ligands for the orphan receptor Tie1. The HS–Tie1 interaction promoted Tie1–Tie2 heterodimerization and enhanced Tie1 stability within the mature vasculature. Loss of HS–Tie1 binding using CRISPR–Cas9-mediated mutagenesis in vivo led to decreased Tie protein levels, pathway suppression and aberrant retinal vascularization. Together, these results reveal that sulfated glycans use dual mechanisms to regulate Ang–Tie signaling and are important for the development and maintenance of the vasculature

Radio Astronomy

Contains reports on three research projects, with one broken into two subsections.National Aeronautics and Space Administration (Grant NsG-419)National Aeronautics and Space Administration (Contract NSR-22-009-120)Joint Services Electronics Programs (U.S. Army, U.S. Navy, and U.S. Air Force) under Contract DA 28-043-AMC-02536(E