Physical characterization of uranium oxide pellets and powder applied in the Nuclear Forensics International Technical Working Group Collaborative Materials Exercise 4

Journal of Radioanalytical and Nuclear Chemistry - Physical characterization is one of the most broad and important categories of techniques to apply in a nuclear forensic examination. Physical...     

Ruthenium‐Containing Linear Helicates and Mesocates with Tuneable p53‐Selective Cytotoxicity in Colorectal Cancer Cells

The ligands L¹ and L² both form separable dinuclear double‐stranded helicate and mesocate complexes with Ru^II. In contrast to clinically approved platinates, the helicate isomer of [Ru₂( L¹ )₂]⁴⁺ was preferentially cytotoxic to isogenic cells (HCT116 p53^?/?), which lack the critical tumour suppressor gene. The mesocate isomer shows the reverse selectivity, with the achiral isomer being preferentially cytotoxic towards HCT116 p53^+/+. Other structurally similar Ru^II‐containing dinuclear complexes showed very little cytotoxic activity. This study demonstrates that alterations in ligand or isomer can have profound effects on cytotoxicity towards cancer cells of different p53 status and suggests that selectivity can be “tuned” to either genotype. In the search for compounds that can target difficult‐to‐treat tumours that lack the p53 tumour suppressor gene, [Ru₂( L¹ )₂]⁴⁺ is a promising compound for further development.     

Gln-Gly cleavage: a dominant dissociation site in the fragmentation of protonated peptides

An understanding of the gas-phase dissociation of protonated peptides within the mass spectrometer is essential for automated high-throughput protein identification. In this communication we describe a facile cleavage of the Gln-Gly peptide bond under low-collisional energy conditions. A variety of synthetic peptides have been analysed where key amino acids have been substituted within the sequence PQGPPQQGGR, which is a consensus repeat present in the tryptic peptides of acidic proline-rich protein 1 (PRP-1). The collision-induced dissociation spectra obtained from the PRP-1 tryptic peptides and the synthetic peptides indicate that facile Gln-Gly cleavage occurs when an X-Gln-Gly-Y sequence is present in a peptide, where X is any amino acid and Y any amino acid other than Gly.     

Inducing structural polarity using fluorinated organics: X-ray crystal structures of p-XC6F4CN (X = Cl,Br, I)

Non-centrosymmetric structures are promoted through the use of perfluoroaromatics containing structure-directing CN...X (X = Br, I) supramolecular synthons.     

Approaches to charge calculations in molecular mechanics

Alternative methods of estimating atomic charges in haloalkanes are presented, derived from quantum mechanical and classical treatments. A scheme based on a breakdown of the transmission of charge by polar atoms into one-bond, two-bond, and three-bond additive contributions is given, in which the one-bond effect is proportional to the difference in the electronegativities of the bonded atoms, and the two- and three-bond effects functions of the atomic electronegativity and polarizability. Suitable developments of the basic scheme, including an iterative self-consistent process, give calculated dipole moments for a variety of haloalkanes in good agreement with the observed values. The atomic charges obtained by this scheme are compared with other estimates of these charges. They are similar to those derived from a simple LCAO –MO scheme but differ from those obtained by population analysis of more refined quantum mechanical calculations.     

Thermochemistry of Binding of Lead(II) and Cadmium(II) by Saccharides in Aqueous Solution

Solution calorimetry was used to determine enthalpies and stability constants for binding of lead(II) or cadmium(II) by galacturonic acid and several monosaccharides in aqueous solution. New values for enthalpies of solution in water are reported for galacturonic acid and maltose monohydrate. The interaction of water solvent with the reactants is the largest factor in the binding process.     

Localized defects in classical one-dimensional models

Several aspects of localized defects in the Frenkel-Kontorova, classicalXY chain and analogous models with a finite range of interactions are discussed from a general point of view. Precise definitions are given for defect phase shifts (charges) and for creation, pinning, and interaction energies. Corresponding definitions are also provided for interfaces (localized regions separating two phases). For the nearest-neighbor Frenkel-Kontorova model, the various defect energies are related to areas enclosed by contours joining heteroclinic points of the area-preserving map generated by the conditions of mechanical equilibrium.     

An approximately divergence-free 9-node velocity element (with variations) for incompressible flows

Explicit basis functions are constructed for 9-node biquadratic velocity fields which guarantee that a weak form of the continuity equation is satisfied. The corresponding pressure approximations are either piecewise constant, piecewise linear or piecewise bilinear. These results are extended to give bases for bilinear velocity/piecewise constant pressure elements and also to some three-dimensional brick elements.     

Inhibierung der Autoxydation von Polypropylenoxid durch KOH

Ohne Zusammenfassung     

A Newman-Penrose-type formalism for space-times with torsion

The familiar Newman-Penrose formalism, in which the curvature of space-time is represented in terms of spin coefficients, is here extended to include the possibility of an asymmetric connection. It is hoped that this approach will be useful in dealing with certain problems in Einstein-Cartan theory, and also in other theories of gravitation that include torsion.