Oxidation and Polymerization of Soybean Biodiesel/Petroleum Diesel Blends

Fuels in modern diesel engine fuel systems are exposed to highly oxidizing conditions, thus it is important to understand their degradation mechanisms. A range of chemical and physical properties was monitored during the oxidation and polymerization of soybean methyl ester biodiesel (B100), a diesel fuel (B0), and their blends (B10, B30) at 90 °C with aeration. The initial rapid oxidation of polyunsaturated fatty acid methyl esters (FAMEs) provided a transient pool of peroxides that led to the formation of aldehydes, ketones, and acids as secondary products. Monounsaturated and saturated FAMEs were oxidized concurrently with polyunsaturated FAMEs in B10, B30, and B100, but only B100 showed significant oxidation reactions continuing after the polyunsaturated FAMEs were depleted. New esters were a major oxidation product, eventually comprising 40–60% of the incorporated oxygen. Carboxylic acids and alcohols react to form esters and water, with vaporization of water driving the equilibrium toward ester formation. Polymers with ester linkages are likely contributors to the higher molecular weight materials formed and resulting increase in viscosity under these conditions

Smoke Point Measurements of Diesel-Range Hydrocarbon–Oxygenate Blends Using a Novel Approach for Fuel Blend Selection

The use of oxygenated fuels decreases particulate matter (PM) emissions from diesel engines. Studies using engines, experimental flames, and modeling have shown that the decrease in soot emissions depends on the oxygenate molecular structure. To provide a better understanding of the complex processes occurring in engines leading to PM emissions, fundamental and systematic studies of the sooting tendency trends for diesel-range hydrocarbon–oxygenate blends are needed. We present a new approach to selecting fuel blends for sooting tendency measurements that minimizes the confounding effect of dilution of highly sooting components in the base fuel by maintaining constant concentrations of those components in the blends. This novel approach is illustrated by sooting tendency (smoke point) measurements in a diffusion flame for a variety of diesel-range hydrocarbon–oxygenate blends with different molecular structures. The oxygenates included primary alcohols (1-butanol, 1-undecanol), diesters (dibutyl succinate, dibutyl maleate), esters (methyl decanoate and methyl oleate), and a glycol triether (tri­(propylene glycol) methyl ether). The hydrocarbons included an aromatic (1,2,4-trimethylbenzene), a straight-chain alkane (<i>n</i>-hexadecane), and a highly branched alkane (2,2,4,4,6,8,8-heptamethylnonane). The fuels were investigated as three-component blends, with an oxygenate in a hydrocarbon base fuel consisting of a highly sooting hydrocarbon component (1,2,4-trimethylbenzene) and a low-sooting hydrocarbon (<i>n</i>-hexadecane). The oxygen-extended sooting index (OESI) provided sooting tendency trends that were generally consistent with expectations for both hydrocarbon-only and oxygenated fuels. The dominant chemical structure factors influencing the sooting tendency of the hydrocarbons were aromaticity and branching. For the oxygenates, the primary alcohols, the saturated monoester, and the glycol triether exhibited the lowest sooting tendency, followed by the shorter-chain diesters, and then the unsaturated monoester, with unsaturation increasing the sooting tendency

Refining Economics of U.S. Gasoline: Octane Ratings and Ethanol Content

Increasing the octane rating of the U.S. gasoline pool (currently ∼93 Research Octane Number (RON)) would enable higher engine efficiency for light-duty vehicles (e.g., through higher compression ratio), facilitating compliance with federal fuel economy and greenhouse gas (GHG) emissions standards. The federal Renewable Fuels Standard calls for increased renewable fuel use in U.S. gasoline, primarily ethanol, a high-octane gasoline component. Linear programming modeling of the U.S. refining sector was used to assess the effects on refining economics, CO₂ emissions, and crude oil use of increasing average octane rating by increasing (i) the octane rating of refinery-produced hydrocarbon <u>b</u>lendstocks for <u>o</u>xygenate <u>b</u>lending (BOBs) and (ii) the volume fraction (Exx) of ethanol in finished gasoline. The analysis indicated the refining sector could produce BOBs yielding finished E20 and E30 gasolines with higher octane ratings at modest additional refining cost, for example, ∼1¢/gal for 95-RON E20 or 97-RON E30, and 3–5¢/gal for 95-RON E10, 98-RON E20, or 100-RON E30. Reduced BOB volume (from displacement by ethanol) and lower BOB octane could (i) lower refinery CO₂ emissions (e.g., ∼ 3% for 98-RON E20, ∼ 10% for 100-RON E30) and (ii) reduce crude oil use (e.g., ∼ 3% for 98-RON E20, ∼ 8% for 100-RON E30)

Adsorption and Desorption of Mixtures of Organic Vapors on Beaded Activated Carbon

In this study, adsorption and desorption of mixtures of organic compounds commonly emitted from automotive painting operations were experimentally studied. A mixture of two alkanes and a mixture of eight organic compounds were adsorbed onto beaded activated carbon (BAC) and then thermally desorbed under nitrogen. Following both adsorption and regeneration, samples of the BAC were chemically extracted. Gas chromatography–mass spectrometry (GC-MS) was used to quantify the compounds in the adsorption and desorption gas streams and in the BAC extracts. In general, for both adsorbate mixtures, competitive adsorption resulted in displacing low boiling point compounds by high boiling point compounds during adsorption. In addition to boiling point, adsorbate structure and functionality affected adsorption dynamics. High boiling point compounds such as <i>n</i>-decane and 2,2-dimethylpropylbenzene were not completely desorbed after three hours regeneration at 288 °C indicating that these two compounds contributed to heel accumulation on the BAC. Additional compounds not present in the mixtures were detected in the extract of regenerated BAC possibly due to decomposition or other reactions during regeneration. Closure analysis based on breakthrough curves, solvent extraction of BAC and mass balance on the reactor provided consistent results of the amount of adsorbates on the BAC after adsorption and/or regeneration

Two-Dimensional Modeling of Volatile Organic Compounds Adsorption onto Beaded Activated Carbon

A two-dimensional heterogeneous computational fluid dynamics model was developed and validated to study the mass, heat, and momentum transport in a fixed-bed cylindrical adsorber during the adsorption of volatile organic compounds (VOCs) from a gas stream onto a fixed bed of beaded activated carbon (BAC). Experimental validation tests revealed that the model predicted the breakthrough curves for the studied VOCs (acetone, benzene, toluene, and 1,2,4-trimethylbenzene) as well as the pressure drop and temperature during benzene adsorption with a mean relative absolute error of 2.6, 11.8, and 0.8%, respectively. Effects of varying adsorption process variables such as carrier gas temperature, superficial velocity, VOC loading, particle size, and channelling were investigated. The results obtained from this study are encouraging because they show that the model was able to accurately simulate the transport processes in an adsorber and can potentially be used for enhancing absorber design and operation

<em>Neisseria gonorrhoeae</em> Suppresses Dendritic Cell-Induced, Antigen-Dependent CD4 T Cell Proliferation

<div><p><em>Neisseria gonorrhoeae</em> is the second most common sexually transmitted bacterial pathogen worldwide. Diseases associated with <em>N. gonorrhoeae</em> cause localized inflammation of the urethra and cervix. Despite this inflammatory response, infected individuals do not develop protective adaptive immune responses to <em>N. gonorrhoeae</em>. <em>N. gonorrhoeae</em> is a highly adapted pathogen that has acquired multiple mechanisms to evade its host's immune system, including the ability to manipulate multiple immune signaling pathways. <em>N. gonorrhoeae</em> has previously been shown to engage immunosuppressive signaling pathways in B and T lymphocytes. We have now found that <em>N. gonorrhoeae</em> also suppresses adaptive immune responses through effects on antigen presenting cells. Using primary, murine bone marrow-derived dendritic cells and lymphocytes, we show that <em>N. gonorrhoeae</em>-exposed dendritic cells fail to elicit antigen-induced CD4+ T lymphocyte proliferation. <em>N. gonorrhoeae</em> exposure leads to upregulation of a number of secreted and dendritic cell surface proteins with immunosuppressive properties, particularly Interleukin 10 (IL-10) and Programmed Death Ligand 1 (PD-L1). We also show that <em>N. gonorrhoeae</em> is able to inhibit dendritic cell- induced proliferation of human T-cells and that human dendritic cells upregulate similar immunosuppressive molecules. Our data suggest that, in addition to being able to directly influence host lymphocytes, <em>N. gonorrhoeae</em> also suppresses development of adaptive immune responses through interactions with host antigen presenting cells. These findings suggest that gonococcal factors involved in host immune suppression may be useful targets in developing vaccines that induce protective adaptive immune responses to this pathogen.</p> </div

<i>N. gonorrhoeae</i> inhibits dendritic cell-induced T cell proliferation in human primary immune cells.

<p><b>A</b>) Representative histograms from 2 donors showing unregulated expression of CD11c, HLA-DR, CD274 and CD273 at 24 hours post stimulation with <i>N. gonorrhoeae</i> (MOI = 1, 10). <b>B</b>) IL-10 protein production by human DCs treated with <i>N. gonorrhoeae</i> (MOI = 1,10). <b>C</b>) MFI of PD-L1 expression on human DCs treated with <i>N. gonorrhoeae</i> (MOI = 1,10). <b>D</b>) <i>N. gonorrhoeae</i> inhibits human DCs induced allogeneic T cell proliferation in the Mixed Lymphocyte Reaction (MLR). CFSE proliferation profiles of CD4+ cells after non-adherent cells (NAD) co-cultured with human DCs treated with medium or <i>N. gonorrhoeae</i> (MOI = 10) for 7 days at the ratio of 10∶1.</p

<i>N. gonorrhoeae</i> inhibits BMDC antigen-induced T cell proliferation.

<p>BMDCs were exposed to <i>N. gonorrhoeae</i> at different MOIs with or without OVA for 24 hours and then co-cultured with CFSE-loaded OT-II T cells for seven days. T cell proliferation to OVA was assessed by flow cytometric analysis. <b>A</b>) Representative gating strategy of CD4+ Vβ5+ OT-II T cells. <b>B</b>) Representative T cell proliferation following co-culture with medium only-treated BMDCs. <b>C</b>) Representative T cell proliferation following co-culture with OVA (100 µg/mL) pulsed BMDCs. <b>D</b>) Representative T cell proliferation profile following co-culture with <i>N. gonorrhoeae</i> (MOI = 1) exposed BMDCs. <b>E</b>) Representative T cell proliferation following co-culture with <i>N. gonorrhoeae</i> (MOI = 1) plus OVA (100 µg/mL) pulsed BMDCs. <b>F</b>) Percentage of OT-II T cell OVA-induced proliferation with a dose range of <i>N. gonorrhoeae</i> (0.01–10 MOI)-exposed BMDCs. Data are mean ± standard deviation (N = 8–32). G. OVA (100 µg/mL) pulsed BMDC were treated with different <i>N. gonorrhoeae</i> strains (White bars: FA1090; Gray bars: MS11; Black bars: F62) at the indicated doses (MOI 0.1–10). Antigen-induced T cell proliferation was assessed after co-culture of the <i>N. gonorrhoeae</i> and OVA treated BMDC with CFSE-loaded OT-II T cells for seven days as noted above. The percentages of proliferated T cells are plotted. Data are mean ± standard deviation (N = 3).</p

IL-10 inhibits OVA-DC-induced T cell proliferation.

<p>OVA-pulsed dendritic cells were co-cultured with CFSE-loaded OT-II T cells with or without IL-10 for seven days. <b>A</b>) Representative histogram overlay and bar graph show T cell proliferation profiles following culture with OVA-pulsed DCs (black) or OVA-pulsed DCs+IL-10 (red). The bar graph shows the proliferation of OT-II T cell in the presence of OVA-pulsed DCs with and without exogenous IL-10 from three independent experiments. Data are mean ± standard deviation (N = 3). <b>B</b>) Transwell experiment scheme. WT OVA-DC with OT-II T cell co-culture was placed in all transwell plates. In the insert medium treated-DCs or <i>N. gonorrhoeae</i>-treated DCs from wild type or <i>Il10^−/−</i> were co-cultured with OT-II T cells as indicated. T cell proliferation from the transwell plate is shown in the histogram overlays. OVA-induced T cell proliferation in the plate was inhibited by <i>N. gonorrhoeae</i>-treated wild type DCs in the insert (red) but not by wild type medium treated-DCs in the insert (blue). OVA-induced T cell proliferation in the plate was the same for <i>N. gonorrhoeae</i>-treated <i>Il10^−/−</i> DCs in the insert (green) and medium treated <i>Il10^−/−</i> DCs in the insert (purple). <b>C</b>) Ratio of proliferated T cells from transwell plates with inserts supplying <i>N. gonorrhoeae</i>-OVA-DCs or medium-DCs. Ratio of T cell proliferation in the plate was obtained by dividing the <i>N. gonorrhoeae</i>-OVA-DCs insert by medium-DCs insert. The black bars represent proliferation ratio from transwell plate supplied with wild type BMDCs in insert (N = 8), the open bars represent proliferation ratio from transwell plate supplied with <i>Il10^−/−</i> BMDCs in insert (N = 4).</p

Fold change in genes over-expressed in BMDCs with <i>N. gonorrhoeae</i> (MOI = 1) plus OVA versus OVA only.

<p>Fold change in genes over-expressed in BMDCs with <i>N. gonorrhoeae</i> (MOI = 1) plus OVA versus OVA only.</p