Effective spin spin interactions in the damped ferromagnets

Simanek's theory is extended by taking into account the nuclear spin excitations due to the motion of the electronic system. Damping of the magnons is found to be an extra criteria for having a finite interaction range for the nuclear spin system. The resonance excitation of Simanek's theory is due to the neglect of the second order in the hyperfine interaction.     

Noncoplanar correlation spectra from the 2H(p, 2p)n reaction at Einc = 44.9 MeV

The differential cross section $\text{d}{}^3\text{σ/}\text{d}\text{Ω}{}_3\text{d}\text{Ω}{}_4\text{d}\text{E}{}_3$ for the ²H(p, 2p)n reaction at E_inc = 44.9 MeV is measured in noncoplanar geometry. The Amado model in general gives a good fit to the absolute cross section. The dependence of the cross section on the momentum of the undetected particle Q₅, on the scattering angle θ₃₄, as well as on the angle of the undetected particle is investigated.     

A Melnikov Method for Homoclinic Orbits with Many Pulses

We present an extension of the Melnikov method which can be used for ascertaining the existence of homoclinic and heteroclinic orbits with many pulses in a class of near‐integrable systems. The Melnikov function in this situation is the sum of the usual Melnikov functions evaluated with some appropriate phase delays. We show that a nonfolding condition which involves the logarithmic derivative of the Melnikov function must be satisfied in addition to the usual transversality conditions in order for homoclinic orbits with more than one pulse to exist. (Accepted December 2, 1996)     

Natural Product Rottlerin Derivatives Targeting Quorum Sensing

Rottlerin is a natural product consisting of chalcone and flavonoid scaffolds, both of which have previously shown quorum sensing (QS) inhibition in various bacteria. Therefore, the unique rottlerin scaffold highlights great potential in inhibiting the QS system of Pseudomonas aeruginosa. Rottlerin analogues were synthesised by modifications at its chalcone- and methylene-bridged acetophenone moieties. The synthesis of analogues was achieved using an established five-step synthetic strategy for chalcone derivatives and utilising the Mannich reaction at C6 of the chromene to construct morpholine analogues. Several pyranochromene chalcone derivatives were also generated using aldol conditions. All the synthetic rottlerin derivatives were screened for QS inhibition and growth inhibition against the related LasR QS system. The pyranochromene chalcone structures displayed high QS inhibitory activity with the most potent compounds, 8b and 8d, achieving QS inhibition of 49.4% and 40.6% and no effect on bacterial growth inhibition at 31 µM, respectively. Both compounds also displayed moderate biofilm inhibitory activity and reduced the production of pyocyanin.     

Ionic peptide aggregation: exploration of conformational dynamics in aqueous solution by computational techniques

The effects of end groups on KEK peptide conformational characteristics and self-assembling properties in water solution are investigated by using long lasting all-atom molecular dynamics simulations. The analysis of the structural macroscopic and microscopic properties and the examination of intra- and intermolecular interactions suggest, in agreement with experimental observations, the role played by side chains and terminal regions in determining the characteristic features of the assemblages. Competition between intra- and interchain interactions greatly affects the diffusivity of peptide molecules and the conformational space that they can sample, ultimately controlling the shape, size, and distribution of the aggregate configurations. Different peptide end groups influence peptide flexibility and seem to play a crucial role in determining the aggregates' supramolecular architectures.     

Sorption and kinetic properties of radiocesium-selective organomineral sorbents

Comparative analysis of the sorption and kinetic properties was carried out for organomineral sorbents synthesized by two routes: (1) from an organomineral suspension and (2) from aqueous-organic solutions.     

A Motif for Infinite Metal Atom Wires

A new motif for infinite metal atom wires with tunable compositions and properties is developed based on the connection between metal paddlewheel and square planar complex moieties. Two infinite Pd chain compounds, [Pd₄(CO)₄(OAc)₄Pd(acac)₂] 1 and [Pd₄(CO)₄(TFA)₄Pd(acac)₂] 2 , and an infinite Pd? Pt heterometallic chain compound, [Pd₄(CO)₄(OAc)₄Pt(acac)₂] 3 , are identified by single‐crystal X‐ray diffraction analysis. In these new structures, the paddlewheel moiety is a Pd four‐membered ring coordinated by bridging carboxylic ligands and μ₂ carbonyl ligands. The planar moiety is either Pd(acac)₂ or Pt(acac)₂ (acac=acetylacetonate). These moieties are connected by metallophilic interactions. The results showed that these one‐dimensional metal wire compounds have photoluminescent properties that are tunable by changing ligands and metal ions. 3 can also serve as a single source precursor for making Pd₄Pt bimetallic nanostructures with precise control of metal composition.     

Exploiting the high-affinity phosphonate–hydroxyapatite nanoparticle interaction for delivery of radiation and drugs

Hydroxyapatite is biocompatible and used in various biomedical applications. Here, we generated hydroxyapatite nanoparticles (HNPs) of various sizes (40–200 nm) and demonstrated that they can be stably loaded with drugs or radioisotopes by exploiting the high-affinity HA–(poly)phosphonate interaction. Clinically available phosphonates, clodronate, and Tc-99m-methylene-diphosphonate (Tc-99m-MDP), were efficiently loaded onto HNPs within 15 min. Biodistribution of radiolabeled HNP-MDP-Tc99m in mice was monitored non-invasively using microSPECT-CT. Imaging and dosimetry studies indicated that the HNPs, regardless of size, were quickly taken up by Kupffer cells in the liver after systemic administration into mice. Clodronate loaded onto HNPs remained biologically active and were able to result in selective depletion of Kupffer cells. This method of drug or isotope loading on HA is fast and easy as it eliminates the need for additional surface modifications of the nanoparticles.     

On the question of self-trapping of positrons in indium

The Doppler-broadening of the positron annihilation line in 5N indium has been studied over the temperature range 77 K to 427 K. No evidence for self-trapping has been discovered; rather, the prevacancy rise in the F-parameter appears linear. The best value for E_V is 0.59±0.03 eV.