ABSTRACT
Amorphous- and nanocrystalline-silicon thin-film photovoltaic modules are made in high-throughput manufacturing lines that necessitate quickly cleaning the reactor. Using NF3, a potent greenhouse gas, as the cleaning agent triggered concerns as recent reports reveal that the atmospheric concentrations of this gas have increased significantly. We quantified the life-cycle emissions of NF3 in photovoltaic (PV) manufacturing, on the basis of actual measurements at the facilities of a major producer of NF3 and of a manufacturer of PV end-use equipment. From these, we defined the best practices and technologies that are the most likely to keep worldwide atmospheric concentrations of NF3 at very low radiative forcing levels. For the average U.S. insolation and electricity-grid conditions, the greenhouse gas (GHG) emissions from manufacturing and using NF3 in current PV a-Si and tandem a-Si/nc-Si facilities add 2 and 7 g CO2(eq)/kWh, which can be displaced within the first 1-4 months of the PV system life.
Subject(s)
Air Pollutants/analysis , Electric Power Supplies , Electronic Waste/analysis , Fluorides/analysis , Industrial Waste/analysis , Nitrogen Compounds/analysis , Atmosphere/chemistry , Environmental Monitoring , Manufactured Materials/analysis , Solar Energy , Waste Management/methodsABSTRACT
Antigen stimulation of lymphocytes induces upregulation of phospholipase D (PLD) activity, but the biological significance of PLD-mediated signaling in T cells has not been well established. Here we demonstrate that PLD signaling is essential for proliferation of mouse CD8(+) T cells and CD4(+)CD25(-) T cells, but is not required for proliferation of CD4(+)CD25(+) regulatory T cells. We exploited this observation to develop an efficient method to enrich for regulatory T cells starting from preparations of total CD4(+) T lymphocytes. Inhibition of PLD signaling blocked effector T-cell proliferation after T cell-antigen receptor (TCR) engagement, but had no significant effect on the proliferation of CD4(+)CD25(+) T cells with regulatory functions. Consequently, cells expanded in vitro for one week by antigen receptor stimulation with PLD signal inhibition were markedly enriched for regulatory T cells.
