Vapoluminescent Behavior and the Single-Crystal-to-Single-Crystal Transformations of Chloroform Solvates of [Au2(μ-1,2-bis(diphenylarsino)ethane)2](AsF6)2

The mono- and di-chloroform solvates of [Au₂(μ-1,2-bis(diphenylarsino)ethane)₂](AsF₆)₂ undergo single-crystal-to-single-crystal transformations that result in gain (over 12 hours) or slow loss (over five years) of only one chloroform molecule. The change in solvation results in changes in the structure and luminescence of the digold cation. The cation consists of a pair of slightly bent As-Au-As units that are connected through the two bridging dpae ligands and by aurophilic interactions with Au⋅⋅⋅Au contacts of 3.05152(15) Å in the disolvate or 2.9570(5) Å in the monosolvate.     

The synthesis of luminescent lanthanide-based chemosensors for the detection of zinc ions

Herein, we report the synthesis of two lanthanide-based chemosensors, Tb-5 and Eu-6, designed to sense free zinc ions (Zn²⁺) in aqueous solutions. The Tb-5 complex features a bis(2-pyridinylmethyl)amine moiety as a zinc(II)-responsive lanthanide-sensitising ‘antenna’, while Eu-6 incorporates a quinoline-based moiety for this purpose. Luminescence enhancements of 210% and 340% are observed upon addition of Zn²⁺ ions to Tb-5 and Eu-6, respectively. Both sensors are selective for Zn²⁺ ions over several other cations of environmental significance.     

The contribution of 2N photon absorption in C(γ,2N) reactions for Eγ = 150–400 MeV

The ¹²C(γ,pn) and ¹²C(γ,pp) reactions have been studied using tagged photons of energy E_γ = 150–400 MeV. Recoil momentum distributions are compared to the results of Monte Carlo calculations based on a two-nucleon photon absorption model and two different phase space models. The ¹²C(γ,pn) data at low missing energy are consistent with absorption on 1p² and 1s1p nucleon pairs.     

Anion‐Mediated Effects on the Size and Mechanical Properties of Enzymatically Crosslinked Suckerin Hydrogels

The suckerin family of proteins, identified from the squid sucker ring teeth assembly, offers unique mechanical properties and potential advantages over other natural biomaterials. In this study, a small suckerin isoform, suckerin‐12, is used to create enzymatically crosslinked, macro‐scale hydrogels. Upon exposure to specific salt conditions, suckerin‐12 hydrogels contracted into a condensed state where mechanical properties are found to be modulated by the salt anion present. The rate of contraction is found to correlate well with the kosmotropic arm of the Hofmeister anion series. However, the observed changes in hydrogel mechanical properties are better explained by the ability of the salt to neutralize charges in suckerin‐12 by deprotonization or charge screening. Thus, by altering the anions in the condensing salt solution, it is possible to tune the mechanical properties of suckerin‐12 hydrogels. The potential for suckerins to add new properties to materials based on naturally‐derived proteins is highlighted.     

Curcumin Loaded Dendrimers Specifically Reduce Viability of Glioblastoma Cell Lines

Glioblastoma (GB) is a deadly and aggressive cancer of the CNS. Even with extensive resection and chemoradiotherapy, patient survival is still only 15 months. To maintain growth and proliferation, cancer cells require a high oxidative state. Curcumin, a well-known anti-inflammatory antioxidant, is a potential candidate for treatment of GB. To facilitate efficient delivery of therapeutic doses of curcumin into cells, we encapsulated the drug in surface-modified polyamidoamine (PAMAM) dendrimers. We studied the in vitro effectiveness of a traditional PAMAM dendrimer (100% amine surface, G4 NH₂), surface-modified dendrimer (10% amine and 90% hydroxyl-G4 90/10-Cys), and curcumin (Cur)-encapsulated dendrimer (G4 90/10-Cys-Cur) on three species of glioblastoma cell lines: mouse-GL261, rat-F98, and human-U87. Using an MTT assay for cell viability, we found that G4 90/10-Cys-Cur reduced viability of all three glioblastoma cell lines compared to non-cancerous control cells. Under similar conditions, unencapsulated curcumin was not effective, while the non-modified dendrimer (G4 NH₂) caused significant death of both cancerous and normal cells. By harnessing and optimizing the components of PAMAM dendrimers, we are providing a promising new route for delivering cancer therapeutics. Our results with curcumin suggest that antioxidants are good candidates for treating glioblastoma.     

Single and double πo-photoproduction from the deuteron

Photoproduction of neutral pions from the deuteron has been studied for incident photon energies from 200 MeV to 792 MeV with the TAPS detector at the Mainz MAMI accelerator. Total and differential cross sections covering the full angular range have been obtained for coherent and incoherent single π^o-photoproduction. Good agreement between model predictions and the data was found for the coherent process. The incoherent cross section in the energy region of the Δ(1232)-resonance is overestimated by existing models. A comparison to model predictions indicates that final state interaction effects are much more important than for the coherent reaction. However, the angular dependence of the data in the Δ-peak region follows the pattern expected from the dominant excitation of the M₁₊-multipole on the free nucleon. The energy and angular dependence of single π^o-photoproduction in the second resonance region is remarkably different from the reaction on the free proton, indicating a strong nuclear effect. Finally the total cross section for double π^o-photoproduction from the deuteron has been measured for the first time and was used to estimate the cross section for double π^o-photoproduction from the neutron. Received: 24 June 1999 / Revised version: 30 August 1999     

5‐Hydroxyl Hydantoins via One‐Pot Microwave‐Assisted Air Oxidation of Ugi Products

The novel and one‐pot synthesis of 5‐hydroxyl hydantoins from Ugi five‐component condensation procedures is reported. The transformation was promoted via a microwave heating method and provided 5‐hydroxyl hydantoins in workable yields, representing a direct approach to this synthetically challenging and biologically interesting pharmacophore.     

Characterization of Fibers in an Existing Network for High Speed System (10Gb/s or Greater) Compatibility

With OC-192 communications systems being commercially available and higher bit rate systems in development, prudent telecommunications network administrators are testing their installed fibers to determine if they can be successfully used at 10 Gb/s and higher. Together with New Brunswick Telephone (NBTel), the Fiber Optics Group at UNB have tested various installed fibers and cables in the NBTel network for their losses at wavelengths of 1244, 1310, 1550, and 1625 nm, as well as for strain and polarization mode dispersion (PMD). Weather conditions, age, place of installation, and cable types have also been considered. Aging does not seem to affect the performance of the fibers. Although most fibers are high-speed system compatible when looking at attenuation measurements, about 40% of the fibers tested would not meet the 10 Gb/s OC-192 system manufacturer's design guidelines concerning PMD.