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Eliciting neutralizing antibodies is thought to be a key activity of a vaccine against human immunodeficiency virus (HIV). However, a number of studies have suggested that in addition to neutralization, interaction of IgG with Fc gamma receptors (FcγR) may play an important role in antibody-mediated protection. We have previously obtained evidence that the protective activity of the broadly neutralizing human IgG1 anti-HIV monoclonal antibody (MAb) b12 in macaques is diminished in the absence of FcγR binding capacity. To investigate antibody-dependent cellular cytotoxicity (ADCC) as a contributor to FcγR-associated protection, we developed a nonfucosylated variant of b12 (NFb12). We showed that, compared to fully fucosylated (referred to as wild-type in the text) b12, NFb12 had higher affinity for human and rhesus macaque FcγRIIIa and was more efficient in inhibiting viral replication and more effective in killing HIV-infected cells in an ADCC assay. Despite these more potent in vitro antiviral activities, NFb12 did not enhance protection in vivo against repeated low-dose vaginal challenge in the simian-human immunodeficiency virus (SHIV)/macaque model compared to wild-type b12. No difference in protection, viral load, or infection susceptibility was observed between animals given NFb12 and those given fully fucosylated b12, indicating that FcγR-mediated activities distinct from FcγRIIIa-mediated ADCC may be important in the observed protection against SHIV challenge.

An experimental research on multi-stable mode transitions and hysteresis loops in a high magnetic field helicon wave plasma source is conducted by adjusting matching network parameters. The correspondence relation between the electric circuit and plasma parameters is explored by measuring the plasma absorbed power, plasma electron density, and power transfer efficiency. The details of mode transitions are recorded by measuring the transmission coefficient to understand the feedback effects on the electric circuit from the plasma. Three discharge modes are observed in helicon discharge: the capacitively coupling mode (E mode), the inductively coupling mode (H mode), and the wave coupling mode (W mode). When the plasma absorbed power increases, the discharge mode directly jumps from the E mode to the W mode, while the discharge mode jumps in the order of W–H–E when the plasma absorbed power decreases. In such multi-stable systems, the plasma may be in different modes under the same set of circuit conditions. Hysteresis loops exist even when the dissipative power in the matching network is subtracted, which indicates that the main cause of hysteresis is nonlinearities inside the plasma. [ABSTRACT FROM AUTHOR]

A steady-state, high-flux N2/Ar helicon wave plasma (HWP) with a small diameter (10 mm) was used to nitride the interior of a slender austenitic stainless steel (ASS) 316L tube at a temperature of 450 °C. N2 and Ar were fed to a 500 mm long slender tube with 10 mm inner diameter and were ionized inside the tube using a helicon wave in the magnetic field of 2000 G. The microstructure and depth of the nitrided layers, in addition to the morphology and hardness of the nitrided surfaces, were intensively characterized by employing scanning electron microscopy (SEM), optical microscopy (OM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), as well as microhardness tests. The results confirmed that the nitrided layer consisted primarily of the expanded austenite phase γN, and neither CrN nor iron nitride precipitates. An increasing trend in microhardness was observed in inductively coupled plasma (ICP) and HWP modes; however, the increase in HWP nitriding (up to HV 1820 with a thickness of 14 μm) was approximately 1.5 times greater than that achieved through ICP plasma nitriding. This was owing to the higher N+ ion density in the HWP mode. Considering the successful control of N2 plasma discharge in a slender tube with a small diameter, this study opens up a new avenue for achieving high-yield nitride layers inside slender tubes. [ABSTRACT FROM AUTHOR]