Evaluation of the impacts of gamma radiolysis on an ALSEP process solvent

Journal of Radioanalytical and Nuclear Chemistry - Separating the minor actinide elements (americium and curium) from the fission product lanthanides is an important step in closing the nuclear...     

PI3K-δ and PI3K-γ Inhibition by IPI-145 Abrogates Immune Responses and Suppresses Activity in Autoimmune and Inflammatory Disease Models

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Synthesis,crystal structure studies and solvatochromic behaviour of two 2‐{5‐[4‐(dimethylamino)phenyl]penta‐2,4‐dien‐1‐ylidene}malononitrile derivatives

The synthesis, crystal structure studies and solvatochromic behavior of 2‐{(2E,4E)‐5‐[4‐(dimethylamino)phenyl]penta‐2,4‐dien‐1‐ylidene}malononitrile, C₁₆H₁₅N₃ (DCV[3]), and 2‐{(2E,4E,6E)‐7‐[4‐(dimethylamino)phenyl]hepta‐2,4,6‐trien‐1‐ylidene}malononitrile, C₁₈H₁₇N₃ (DCV[4]), are reported and discussed in comparison with their homologs having a shorter length of the π‐conjugated bridge. The compounds of this series have potential use as nonlinear materials with second‐order effects due to their donor–acceptor structures. However, DCV[3] and DCV[4] crystallized in the centrosymmetric space group P2₁/c which excludes their application as nonlinear optical materials in the crystalline state. They both crystallize with two independent molecules having the same molecular conformation in the asymmetric unit. The series DCV[1]–DCV[4] demonstrated reversed solvatochromic behavior in toluene, chloroform, and acetonitrile.     

Experimental observation and characterization of the magnetorotational instability

Differential rotation occurs in conducting flows in accretion disks and planetary cores. In such systems, the magnetorotational instability can arise from coupling Lorentz and centrifugal forces to cause large radial angular momentum fluxes. We present the first experimental observation of the magnetorotational instability. Our system consists of liquid sodium between differentially rotating spheres, with an imposed coaxial magnetic field. We characterize the observed patterns, dynamics, and torque increases, and establish that this instability can occur from a hydrodynamic turbulent background.     

Aspects of the fundamental chemistry of cesium extraction from acidic media by hccd

It is well known that cesium extraction from acidic media by HCCD proceeds through a liquid-liquid ion exchange extraction mechanism. Four data sets with 25 experimental measurements of Cs distribution ratios, D_Cs=[Cs]_org/[Cs]_aq, at a variety of initial conditions (various concentrations of [HCCD] and [HNO₃]) have been modeled using the SXLSQI computer program developed at ORNL. The SXLSQI program was used in this analysis to help elucidate the general chemical equilibria operative in the extraction of Cs⁺ into an organic phase comprised of HCCD in FS-13. The experimental data sets are best modeled with four chemical equilibria (T= 25°C). The equilibrium constant for the primary exchange reaction of log K_eq=3.07 is in excellent agreement with values reported in the literature of log K_eq=3.00 for the HCCD/nitrobenzene system. In general, the equilibria representing the mechanism of Cs extraction by HCCD are consistent with earlier literature reports, albeit derived by different experimental and modeling schemes.     

Synthesis and structural study of organic two‐photon‐absorbing cycloalkanone chromophores

The three organic two‐photon‐absorbing cycloalkanone chromophores 2,4‐bis[4‐(diethylamino)benzylidene]cyclobutanone, C₂₆H₃₂N₂O ( I ), 2,5‐bis[4‐(diethylamino)benzylidene]cyclopentanone, C₂₇H₃₄N₂O ( II ), and 2,6‐bis[4‐(diethylamino)benzylidene]cyclohexanone, C₂₈H₃₆N₂O ( III ), were obtained by a reaction between 4‐(diethylamino)benzaldehyde and the corresponding cycloalkanone and were characterized by single‐crystal X‐ray diffraction studies, as well as density functional theory (DFT) quantum‐chemical calculations. Molecules of this series have three main fragments, i.e. central acceptor (A) and two terminal donors (D₁ and D₂) and represent examples of the D₁–π–A–π–D₂ molecular design. All three compounds crystallize with two crystallographically independent molecules in the asymmetric unit ( A and B ) and are distinguished by the conformations of both the molecular Et₂N—C₆H₄—C=C—C(=O)—C=C—C₆H₄—NEt₂ backbone (arcuate or linear) and the terminal diethylamino substituents (syn‐ or antiperiplanar to the plane of the molecule). The central four‐ and five‐membered rings in I and II are almost planar, and the six‐membered ring in III adopts a sofa conformation. In the crystals of I – III , the two independent molecules A and B form hydrogen‐bonded [ A … B ] dimers via intermolecular C—H…O hydrogen bonds. Furthermore, the [ A … B ] dimers in I are bound by intermolecular C—H…O hydrogen bonds into two‐tier puckered layers, whereas in the crystals of II and III , the [ A … B ] dimers are stacked along the c and a axes, respectively. Taking into account the decreasing steric strain upon expanding the central ring, compound I might be more efficient as a two‐photon absorption chromophore than compounds II and III , which corresponds to the results of spectroscopic studies.     

A facile synthesis of substituted benzyl selenocyanates

Benzyl selenocyanates can be made from the corresponding benzylic bromides or chlorides in 30-60 minutes using acetonitrile as a solvent. The products may be obtained pure in satisfactory yields without recourse to chromatography.     

Characterization of an effective cleaning procedure for aluminum alloys: surface enhanced Raman spectroscopy and zeta potential analysis

We have developed a cleaning procedure for aluminum alloys for effective minimization of surface-adsorbed sub-micrometer particles and nonvolatile residue. The procedure consists of a phosphoric acid etch followed by an alkaline detergent wash. To better understand the mechanism whereby this procedure reduces surface contaminants, we characterized the aluminum surface as a function of cleaning step using surface enhanced Raman spectroscopy (SERS). SERS indicates that phosphoric acid etching re-establishes a surface oxide of different characteristics, including deposition of phosphate and increased hydration, while the subsequent alkaline detergent wash appears to remove the phosphate and modify the new surface oxide, possibly leading to a more compact surface oxide. We also studied the zeta potential of <5 microm pure aluminum and aluminum alloy 6061-T6 particles to determine how surface electrostatics may be affected during the cleaning process. The particles show a decrease in the magnitude of their zeta potential in the presence of detergent, and this effect is most pronounced for particles that have been etched with phosphoric acid.