No abstract

Efficient manufacturing of increasingly sophisticated biopharmaceuticals requires the development of new breeds of chromatographic materials featuring two or more layers, with each layer affording different functions. This letter reports the in situ modification of a commercial beaded anion exchange adsorbent using atmospheric pressure plasma generated within gas bubbles. The results show that exposure to He-O2 plasma in this way yields significant reductions in the surface binding of plasmid DNA to the adsorbent exterior, with minimal loss of core protein binding capacity; thus, a bi-layered chromatography material exhibiting both size excluding and anion exchange functionalities within the same bead is produced.

The thermalization of water, due to the absorption of laser radiation, offers a way to generate underwater sound from an airborne platform. However, the thermal expansion mechanism that produces sound is notoriously inefficient and the standard technique of amplitude modulation (AM) of the laser intensity is generally inadequate for practical applications such as bathymetry. With the advent of ultra-high repetition rate pulsed lasers, it is now appropriate to take a fresh look at some alternative schemes for modulating the laser intensity. Computer simulations will be shown for three different modulation techniques in comparison with the standard AM technique. These modulation schemes are, respectively, frequency modulation (FM), pulse density modulation, and pulse amplitude modulation. In each case, the parameters controlling the far-field acoustic pressure amplitude will be identified in an attempt to optimize the system. [Work supported by NSF.]