This effort describes laboratory evaluations of six alternative (nonpetroleum) jet fuel candidates derived from coal, natural gas, camelina, and animal fat. Three of the fuels were produced via Fischer-Tropsch (FT) synthesis, while the other three were produced via extensive hydroprocessing. The thermal stability, elastomer swell capability, and combustion emissions of the alternative jet fuels were assessed. In addition, detailed chemical analysis was performed to provide insight into their performance and to infer potential behavior of these fuels if implemented. The fuels were supplied by Sasol, Shell, Rentech, UOP, and Syntroleum Corporation. Chemical analyses show that the alternative fuels were comprised of mostly paraffinic compounds at varying relative concentrations, contained negligible heteroatom species, and were mostly aromatic-free. The six paraffinic fuels demonstrated superior thermal oxidative stability compared to JP-8, and therefore, have increased resistance to carbon formation when heated and can be exposed to higher temperatures when used to cool aircraft systems. Material compatibility tests show that the alternative fuels possess significant seal swelling capability in conditioned nitrile O-rings; however, elastomer swelling was significantly lower than for JP-8, which may likely result in fuel leaks in aircraft systems. Engine tests with the alternative fuels demonstrated no anomalies in engine operation, production of significantly lower nonvolatile particulate matter (soot), and moderately lower unburned hydrocarbons and carbon monoxide emissions compared to baseline JP-8 fuel. Also, no penalty (i.e., increase) in fuel flow requirement for equal engine power output was observed. In general, this study demonstrates that paraffinic fuels derived from different feedstocks and produced via FT synthesis or hydroprocessing can provide fuels with very similar properties to conventional fuels consisting of excellent physical, chemical, and combustion characteristics for use in turbine engines. These types of fuels may be considered as viable drop-in replacement jet fuels if deficiencies such as seal swell, lubricity, and low density can be properly addressed.

Angioimmunoblastic T cell lymphoma (AITL) is an aggressive tumor derived from malignant transformation of T follicular helper (Tfh) cells. AITL is characterized by loss-of-function mutations in Ten-Eleven Translocation 2 (TET2) epigenetic tumor suppressor and a highly recurrent mutation (p.Gly17Val) in the RHOA small GTPase. Yet, the specific role of RHOA G17V in AITL remains unknown. Expression of Rhoa G17V in CD4 T cells induces Tfh cell specification; increased proliferation associated with inducible co-stimulator (ICOS) upregulation and increased phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase signaling. Moreover, RHOA G17V expression together with Tet2 loss resulted in development of AITL in mice. Importantly, Tet2RHOA G17V tumor proliferation in vivo can be inhibited by ICOS/PI3K-specific blockade, supporting a driving role for ICOS signaling in Tfh cell transformation.

High-performance liquid chromatography (HPLC) based techniques are used to investigate the role of polar species in deposit formation during jet fuel autoxidation and to explore the relative contributions of the various species classes which compose the polar fraction. More specifically, HPLC with UV-vis absorption detection was employed to quantify the polar species in jet fuel as a class, and a technique which combines solid-phase extraction (SPE) with HPLC and gas chromatography with mass spectrometric detection (GC-MS) was used to identify the species classes which compose the polar fraction in typical jet fuels. The analytical results were combined with surface deposit data obtained in a quartz crystal microbalance (QCM) system for a series of twenty jet fuels. The results indicate a relationship between the total amount of polar species measured and the amount of surface deposits produced. Results also suggest that phenols, various other oxygenated polar species, indoles, and carbazoles have a significant positive correlation with jet fuel surface deposit formation, while pyridines, anilines, and quinolines do not demonstrate a strong correlation with the tendency of a fuel to form surface deposits.

The production of detrimental carbonaceous deposits in jet aircraft fuel systems results from the involvement of trace heteroatomic species in the autoxidation chain that occurs upon fuel heating. Although it has been known for many years that these sulfur-, nitrogen-, and oxygen-containing species contribute to the tendency of a fuel to form deposits, simple correlations have been unable to predict the oxidation rates or the deposit forming tendencies over a range of fuel samples. In the present work, a chemical kinetic mechanism developed previously is refined to include the roles of key fuel species classes, such as phenols, reactive sulfur species, dissolved metals, and hydroperoxides. The concentrations of these fuel species classes in the unreacted fuel samples are measured experimentally and used as an input to the mechanism. The resulting model is used to simulate autoxidation behavior observed over a range of fuel samples. The model includes simulation of the consumption of dissolved oxygen, as well as the formation and consumption of hydroperoxide species during thermal exposure. In addition, the chemical kinetic mechanism is employed with a global deposition submechanism in computational fluid dynamics (CFD) simulations of deposit formation occurring in nearisothermal as well as non-isothermal flowing environments. Experimental measurements of oxygen consumption, hydroperoxide formation, and deposition are performed for a set of seven fuels. Comparison with experimental measurements indicates that the methodology offers the ability to predict both oxidation and deposition rates in complex flow environments, such as aircraft fuel systems, using only measured chemical species class concentrations for the fuel of interest.