An important constraint on the formation of the building blocks of life in the Hadean is the availability of small, activated compounds such as ammonia (NH(3)) relative to its inert dinitrogen source. Iron-sulfur particles and/or mineral surfaces have been implicated to provide the catalytic active sites for the reduction of dinitrogen. Here we provide a combined kinetic, spectroscopic, and computational modeling study for an alternative source of ammonia from water soluble nitrogen oxide ions. The adsorption of aqueous nitrite (NO(2)(-)) and nitrate (NO(3)(-)) on pyrite (FeS(2)) and subsequent reduction chemistry to ammonia was investigated at 22°C, 70°C, and 120°C. Batch geochemical and in situ Attenuated Total Reflection - Fourier Transform Infrared (ATR-FTIR) spectroscopy experiments were used to determine the reduction kinetics to NH(3) and to elucidate the identity of the surface complexes, respectively, during the reaction chemistry of NO(2)(-) and NO(3)(-). Density functional theory (DFT) calculations aided the interpretation of the vibrational data for a representative set of surface species. Under the experimental conditions used in this study, we detected the adsorption of nitric oxide (NO) intermediate on the pyrite surface. NH(3) production from NO(2)(-) occurred at 70 and 120°C and from NO(3)(-) occurred only at 120°C.

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Inhibitory receptors have been extensively described for their importance in regulating immune responses in chronic infections and cancers. Blocking the function of inhibitory receptors such as PD-1, CTLA-4, 2B4, Tim-3, and LAG-3 has shown promise for augmenting CD8 T cell activity and boosting pathogen-specific immunity. However, the prevalence of inhibitory receptors on CD4 T cells and their relative influence on CD4 T cell functionality in chronic HIV infection remains poorly described. We therefore determined and compared inhibitory receptor expression patterns of 2B4, CTLA-4, LAG-3, PD-1, and Tim-3 on virus-specific CD4 and CD8 T cells in relation to their functional T cell profile. In chronic HIV infection, inhibitory receptor distribution differed markedly between cytokine-producing T cell subsets with, gamma interferon (IFN-γ)- and tumor necrosis factor alpha (TNF-α)-producing cells displaying the highest and lowest prevalence of inhibitory receptors, respectively. Blockade of inhibitory receptors differentially affected cytokine production by cells in response to staphylococcal enterotoxin B stimulation. CTLA-4 blockade increased IFN-γ and CD40L production, while PD-1 blockade strongly augmented IFN-γ, interleukin-2 (IL-2), and TNF-α production. In a Friend retrovirus infection model, CTLA-4 blockade in particular was able to improve control of viral replication. Together, these results show that inhibitory receptor distribution on HIV-specific CD4 T cells varies markedly with respect to the functional subset of CD4 T cells being analyzed. Furthermore, the differential effects of receptor blockade suggest novel methods of immune response modulation, which could be important in the context of HIV vaccination or therapeutic strategies. Inhibitory receptors are important for limiting damage by the immune system during acute infections. In chronic infections, however, their expression limits immune system responsiveness. Studies have shown that blocking inhibitory receptors augments CD8 T cell functionality in HIV infection, but their influence on CD4 T cells remains unclear. We assessed the expression of inhibitory receptors on HIV-specific CD4 T cells and their relationship with T cell functionality. We uncovered differences in inhibitory receptor expression depending on the CD4 T cell function. We also found differences in functionality of CD4 T cells following blocking of different inhibitory receptors, and we confirmed our results in a Friend virus retroviral model of infection in mice. Our results show that inhibitory receptor expression on CD4 T cells is linked to CD4 T cell functionality and could be sculpted by blockade of specific inhibitory receptors. These data reveal exciting possibilities for the development of novel treatments and immunotherapeutics.

Chiral modification of catalysts: A comparative in situ reflection–absorption infrared spectroscopy study of the adsorption of 1‐(1‐naphthyl)ethylamine on Pt surfaces from solution indicated bonding mainly through the amine group and not the aromatic ring as commonly assumed (see picture). In light of these results, a rethinking of the existing model for chiral modification of catalysts may be needed.

The preparation of four-coordinate tetramanganese-amide-hydrazide clusters is described. Reaction of Mn(NR(2))(2) (R = SiMe(3)) with N,N'-diphenylhydrazine resulted in the formation of a black intermediary mixture that converted to a four-coordinate tetranuclear "pinned butterfly" cluster, Mn(4)(μ(3)-N(2)Ph(2))(2)(μ-N(2)Ph(2))(μ-NHPh)(2)(THF)(4). This compound was isolated in ~90% yield and identified by single-crystal X-ray diffraction analysis. In pyridine, the THF ligands were replaced, giving the pyridyl complex Mn(4)(μ(3)-N(2)Ph(2))(2)(μ-N(2)Ph(2))(μ-NHPh)(2)(py)(4). Charge counting considerations indicate that the clusters had gained two protons and two electrons in addition to the formative fragments. Isolation of the black mixture was achieved by extraction techniques from a reaction with a decreased loading of hydrazine run at low temperatures with decreased solvent polarity. The black mixture was characterized by FT-IR, UV-vis, and (1)H NMR spectroscopy. In addition, an isolable, colorless dimer, Mn(2)(μ-NHPh)(2)(NR(2))(2)(THF)(2), was present in the mixture and identified by single-crystal X-ray diffraction. These intermediates are discussed in light of possible mechanisms for formation of the tetranuclear cluster.

The Direct Synthesis, or Rochow Synthesis, involves the reaction of methyl chloride, CH 3 Cl (MeCl), with Cu-Si contact masses (promoted with 1-2% of Zn, Sn, and P) to form methylchlorosilanes. Flow reactor studies (1 bar MeCl at 300°C) showed that contact masses promoted with Zn, Sn, and P (triply promoted) demonstrated the highest Si and MeCl conversion at early reaction times. In situ infrared spectroscopy suggested that in contrast to the doubly promoted catalysts (where CH 3 groups were primarily bound to Si), surface CH 3 showed appreciable binding to the copper component of the triply promoted contact mass. This change in surface composition ultimately led to a drop in reactivity and selectivity of the triply promoted catalyst.

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As the location and accessibility of hydrocarbons is key to understanding and improving the extractability of hydrocarbons in hydraulic fracturing, this study is an attempt to understand how native organics are distributed with respect to pore size to determine the relationship between hydrocarbon chemistry and pore structure in shales.First, selected shale cores from the Eagle Ford and Marcellus formations were subjected to pyrolysis gas chromatography (GC),thermogravimetric analysis, and organic solvent extraction with the resulting effluent analyzed by GC-mass spectrometry (MS). Organics representing the oil and gas fraction (0.1 to 1 wt. %) were observed by GC-MS. For most of the samples, the amount of native organic extracted directly related to the percentage of clay in the shale. The porosity and pore size distribution (0.95 nm to 1.35µm)in the Eagle Ford and Marcellus shales was measured before and after solvent extraction using small angle neutron scattering (SANS). An unconventional method was used to quantify the background from incoherent scattering as the Porod transformation obscures the Bragg peak from the clay minerals. The change in porosity from SANS is indicative of the extraction or breakdown of higher molecular weight bitumen with high