Recombination of germline TCR α and β genes generates polypeptide receptors for MHC peptide. Ag exposure during long-term herpes simplex infections may shape the T cell repertoire over time. We investigated the CD8 T cell response to HSV-2 in chronically infected individuals by sequencing the hypervariable regions encoding TCR α and β polypeptides from T cell clones recognizing virion protein 22 aa 49–57, an immunodominant epitope. The most commonly detected TCRBV gene segment, found in four of five subjects and in 12 of 50 independently derived T cell clones, was TCRBV12-4. Nineteen to seventy-two percent of tetramer-binding cells in PBMCs were stained ex vivo with a TCRBV12 mAb. Three α-chain and three β-chain public TCR sequences were shared between individuals. Public heterodimers were also detected. Promiscuous pairing of a specific TCRVA1-1 sequence with several different TCRB polypeptides was observed, implying a dominant structural role for the TCRA chain for these clonotypes. Functional avidity for cytotoxicity and IFN-γ release was relatively invariant, except for one subject with both high avidity and unique TCR sequences and lower HSV-2 shedding. These data indicate that the CD8 response to a dominant α-herpesvirus epitope converges on preferred TCR sequences with relatively constant functional avidity.
With increasing low-end torque and high-power requirements, passenger vehicle applications need large map-width compressor-stages at high-pressure ratio (3.0 and above). Compressor stages in which wheels operate in a normal housing exhibit limitations in stability at high-pressure ratio and in maximal flow capacity. The application of a ported shroud typically improves the surge characteristics of a centrifugal compressor. In this paper, an optimisation procedure for ported-shroud compressor stages was developed based on Design Of Experiment (DOE) procedure. Two DOE procedures are used. The first one is used to optimize the port location, wheel exducer width and diffuser width; the second is used to optimise the housing volute throat area, diffuser width and diffuser outlet radius. The compressor-stage performance was obtained by using a commercial CFD package. After the first DOE, an experimental DOE with a reduced design space was carried out to obtain the optimised port location and wheel exducer width. After the second DOE and optimization, only most promising configurations were manufactured for tests. The DOEs’ procedures and results as well as the CFD results are discussed and analyzed in the paper. Finally, the relative difference between the CFD and tests are discussed. In comparison to the baseline ported-shroud housing, the final configuration has improved map width by 9%, an increased pressure ratio by 0.2 and a higher peak efficiency by about 1 point.
Compressor housing can greatly impact the behavior of centrifugal compressors used in small turbochargers. This is particularly significant in passenger car applications, where constrains on size and cost of manufacturing pose particular challenges to maintaining aerodynamic efficiency. This paper describes the development of a new compressor housing that overcomes these issues whilst delivering good performance. The concept for the improved design was conceived from an understanding of the loss mechanism inside the housing and the relationship between flow losses and housing geometry. The choice of certain key housing geometric parameters was guided by studies using the Design of Experiment (DOE) method. Computational fluid dynamics (CFD) simulations were also employed in the design of the housing and its use is discussed for several different approaches to the rotor-stator interface. These include a “Mixing Plane”, a “Frozen Rotor” and a “Housing Only” interface model, amongst others. Each differs in its numerical accuracy and computational efficiency and it is important to balance these two factors when choosing a method. Additionally a spreadsheet was built to enable the manipulation of the 3D configuration of the compressor housing. By providing more direct control over the geometry, it reduces the need for extensive and time consuming CAD work. To minimize the fabrication cost for the new housing, die-cast manufacturing was subsequently explored for its smooth surface finish. The final result is a more compact compressor housing that achieves higher efficiency at a lower cost.
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