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The common scanning strategies in Selective Laser Melting lead to an inhomogeneous melt pool intensity distribution throughout the different layers and scan tracks. This results in various defects such as porosity at the edges, residual stresses, or even excessive warping and delamination. In this research, this issue is resolved by the implementation of an on-line and real-time PID feedback controller. The PID feedback controller will alter the laser power based upon the melt pool intensity resulting in a homogeneous intensity distribution throughout the different scan tracks and layers. 2D intensity maps can be generated from the on-line monitoring system during the production of a benchmark part and will serve as validation for the PID feedback controller.
Strong hydrogen-bonding forces between the Thr26 and Thr26′of the protease stabilize the internal cage of the dimeric triad of the aspartyl HIV-1 protease (Asp25Thr26Gly27 and Asp25′Thr26′Gly27′, respectively). The interaction of reversible inhibitors of HIV-1 protease is based on (i) strong hydrogen-bonding forces between the main chain (─CONH─) oxygen atoms of Gly27 and/or Gly27′and hydrogen-bond donating moieties of a drug, and (ii) hydrogen bonds between the oxygen of the catalytic Asp25 and/or Asp25′carboxylates and aliphatic hydroxyl groups of a drug. The free entry of natural substrates into the active-site cavity is sterically hindered by inhibitors, so that the catalytic Asp carboxylates cannot interact with natural substrates. Irreversible inhibitors interact with the nucleophilic carboxylate moiety of Asp25 of HIV-1 protease by covalent bonding.
Until 1963, only viruses were known to stimulate interferon production in cells. The nucleic acid of the virus was generally regarded as the essential stimulus for interferon production.<sup>1</sup>Rotem et al and Isaacs et al<sup>2,3</sup>demonstrated in 1963 that nonviral nucleic acids, provided they were foreign to the cells (heterologous or chemically modified homologous RNA), could also initiate the production of interferon. Although their "foreign nucleic acid" hypothesis was received with some scepticism and retracted later,<sup>4</sup>it offered a reasonable explanation for the nucleic acid-induced resistance to viral infection, which had been described<sup>5</sup>as early as 1953. Moreover, it raised a possible explanation for the antiviral action of agents such as bacteria or apparently nonviral agents as the mold products statolon (culture filtrate of<i>Penicillium stoloniferum</i>) and helenine (mycelium extract of<i>Penicillium funiculosum</i>) which had been found active in a number of experimental viral infections.<sup>6-13</sup>
