Preparation and study of 1,8-di(pyrid-2'-yl)carbazoles

A series of three derivatives of 1,8-di(pyrid-2'-yl)carbazole were prepared by Stille-type coupling of 2-(tri-n-butylstannyl)pyridine with the appropriate 1,8-dibromocarbazole. The carbazoles were prepared by appropriate substitution methodologies on the parent carbazole or by palladium-catalyzed cyclization of di-(p-tolyl)amine to provide the carbazole ring system. An X-ray structure of the di-tert-butyl derivative confirmed that both pyridyl groups were oriented for favorable intramolecular H-bonding to the central N-H. Two orientations of the molecule were found in the unit cell and this observation was corroborated by two N-H stretching bands in the solid state IR. Substitution of N-H by N-D led to increased emission intensity through diminished intramolecular deactivation of the excited state. The di-tert-butyl derivative formed a tridentate complex with Pd(II), which showed a red-shifted band attributed to an intraligand charge transfer state.     

A team decision problem for a convex loss function over aBernoulli random variable

Summary Suppose each member of a team observes aBernoulli random variable,x, and the team outcome is the inner product, a,x, of the observation vectorx and the decision vectora. This paper considers the case when the loss function is convex. Two numerical examples are given.

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Zusammenfassung Angenommen, jedes Mitglied eines Teams beobachtet eineBernoulli-verteilte Zufallsvariablex und das Team-Ergebnis besteht aus dem skalaren Produkt a,x des Beobachtungsvektorsx und des Entscheidungsvektorsa. Die vorliegende Arbeit behandelt den Fall, bei dem die Nutzenfunktion konvex ist. Zwei numerische Beispiele werden vorgeführt.

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A Marketing Team

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Research supported in part by Deutsche Forschungsgemeinschaft while the first author was a guest professor at the Institut für Angewandte Mathematik, Universität Heidelberg. Additional support came from Studiengruppe für Systemforschung, Heidelberg.     

Polarization of atomic transitions in highly ionized15N by beam-foil interaction at 3–8 MeV

The circular polarization parameterS/I for several atomic transitions in¹⁵N was investigated after passage of the nitrogen ions (with energy between 3 and 8 MeV) through a tilted carbon foil. The transitions from high spin states 4608 Å (N IV) and 4940 Å (N V) at 3.5 MeV had largeS/I, 0.18 and 0.25, respectively, which decreased with increasing energy. The 3482 Å (N IV) transition had a maximumS/I at an ion energy of 5.5 MeV (0.05).     

The HydroGEN Consortium: Foundational early stage water-splitting research supporting diversification of the domestic hydrogen supply chain

In the past two years, foundational early-stage materials research through DOE’s HydroGEN Consortium has successfully brought together resources and expertise from industry, academia and the national laboratories to expedite progress in hydrogen production by water-splitting. There is an enormous untapped opportunity to extract hydrogen from water using diverse thermal, chemical and electrochemical process available today at different stages of maturity that can be powered using fossil, nuclear and/or renewable energy. Ongoing development and scale-up of these processes relies on continued scientific and technological innovation, including identification and optimization of new low-cost, high-performance materials for energy conversion, heat transfer, separations, and catalysis. The scientific innovations and accomplishments to date from HydroGEN-supported research are discussed, including impressive results in thermochemistry and photoelectrochemistry, as well as low- and high-temperature electrolysis.     

Some upwinding techniques for finite element approximations of convection-diffusion equations

Summary A uniform framework for the study of upwinding schemes is developed. The standard finite element Galerkin discretization is chosen as the reference discretization, and differences between other discretization schemes and the reference are written as artificial diffusion terms. These artificial diffusion terms are spanned by a four dimensional space of element diffusion matrices. Three basis matrices are symmetric, rank one diffusion operators associated with the edges of the triangle; the fourth basis matrix is skew symmetric and is associated with a rotation by /2. While finite volume discretizations may be written as upwinded Galerkin methods, the converse does not appear to be true. Our approach is used to examine several upwinding schemes, including the streamline diffusion method, the box method, the Scharfetter-Gummel discretization, and a divergence-free scheme.The work of this author was supported by the Office of Naval Research under contract N00014-89J-1440The work of this author was supported through KWF-Landis/Gyr Grant 1496, AT & T Bell Laboratories, and Cray Research     

Gas phase chemical equilibrium in dinitrogen trioxide and dinitrogen tetroxide

The ideal gas chemical thermodynamic properties for NO, NO₂, N₂O₃, and N₂O₄ for the temperature range 50 to 5000 K were evaluated by the statistical thermodynamic method using the most recent molecular parameters. In the calculations for NO and NO₂, the effects of anharmonicity and vibration—rotation interaction were included. The contributions due to centrifugal distortion were also included for NO₂. For evaluation of the thermodynamic properties for N₂O₃ and N₂O₄ molecules, the rigid-rotor and harmonic-oscillator model were adopted. A free internal rotation was assumed for N₂O₃ and an internal rotation barrier height (V₂) of 1.58 kcal mol⁻¹ was derived for N₂O₄. The thermodynamic properties due to hindered internal rotation were clculated using a partition function formed by summation of internal rotation energy levels. The thermodynamic properties for two equilibrium mixtures: NO₂---N₂O₄ and N₂O₃---NO---NO₂---N₂O₄ were also calculated. The effects of temperature and pressure on heat capacities and compositions of these two mixtures are illustrated graphically and the calculated heat capacities and equilibrim constants are in good agreement with available experimental values.     

Metalloimmunotherapy with Rhodium and Ruthenium Complexes: Targeting Tumor-Associated Macrophages

Tumor associated macrophages (TAMs) suppress the cancer immune response and are a key target for immunotherapy. The effects of ruthenium and rhodium complexes on TAMs have not been well characterized. To address this gap in the field, a panel of 22 dirhodium and ruthenium complexes were screened against three subtypes of macrophages, triple-negative breast cancer and normal breast tissue cells. Experiments were carried out in 2D and biomimetic 3D co-culture experiments with and without irradiation with blue light. Leads were identified with cell-type-specific toxicity toward macrophage subtypes, cancer cells, or both. Experiments with 3D spheroids revealed complexes that sensitized the tumor models to the chemotherapeutic doxorubicin. Cell surface exposure of calreticulin, a known facilitator of immunogenic cell death (ICD), was increased upon treatment, along with a concomitant reduction in the M2-subtype classifier arginase. Our findings lay a strong foundation for the future development of ruthenium- and rhodium-based chemotherapies targeting TAMs.     

Paracrystallinity-modulus relationships in kevlar aramid fibers

Meridional x-ray reflections of Kevlar (TM) aramid fibers have been analyzed to provide direct information about fine structure in the direction of the fiber axis. In particular, these reflections have been studied to provide evidence for a one-dimensional paracrystalline structure in Kevlar and to seek quantitative structure-property relationships based on a paracrystalline structure model. In a series of Kevlar fibers an excellent correlation is found between paracrystalline distortion factor g_II and tensile modulus, with g_II decreasing from 2.33% to 1.69% as modulus increases from 75 GPa to 125 GPa. Surprisingly, however, there is no systematic increase in axial crystallite length within this series in spite of heat treatment.     

Hyperfine spectra of KBr and KI

The molecular beam electric resonance technique has been used to conduct a high precision examination of the hyperfine spectra of ³⁹K⁷⁹Br, ³⁹K⁸¹Br and ³⁹K¹²⁷I. Coupling constants for the nuclear electric quadrupole interactions, the spin–rotation interactions, the tensor and scalar spin–spin interactions, as well as the electric dipole moment of KI, and their dependence on vibrational and rotational state have been determined. A few transitions observed for ⁴¹K¹²⁷I show a small shift in the iodine nuclear electric quadrupole interaction, and the fit improves somewhat with the inclusion of an iodine nuclear electric hexadecapole interaction term.