Final state interactions in the parton model and massive lepton pair production

A scheme of assignments for the 0⁺ nonet is proposed with the S¹ (1000) effect corresponding to resonance poles both on Sheet II and Sheet III, and with the ? located somewhere above 1100 MeV, e.g. at 1300 MeV. A tentative fit of the decay characteristics of these and the other nonet condidates, δ(970) and κ(～1200) is achieved with the mixing angle given by cos²θ_S～ 0.13 instead of the ‘ideal’ value of $\text{2}\text{3}$.     

Luminescence of germanate garnets with terbium on dodecahedral and octahedral lattice sites

{Ca(Tb)}₃Ga₂Ge₃O₁₂ and Sr₃[Y(Tb)]₂Ge₃O₁₂ garnets provide a cubic lattice with trivalent terbium, a luminescent rare earth, in dodecahedral (8 oxygen neighbors) and in octahedral (6 oxygen neighbors) sites, respectively. In the materials examined, Tb³⁺ in octahedral sites has a narrower fluorescence emission spectrum, higher luminescence efficiency and a longer lifetime than in dodecahedral sites. The luminescence properties and the unit cell size of the Ca₃Y₂Ge₃O₁₂ garnet, where Tb³⁺ is expected to be located on octahedral sites, are between those of the CaGa and SrY garnets. All these garnets are phosphorescent. On the basis of the variation with temperature of the phosphorescence decay law, it is proposed that the radiative electron-hole recombination process proceeds via a tunneling mechanism at temperatures below the thermal glow peaks, and via a free carrier diffusion mechanism at temperatures above the thermal glow peaks. All three Tb³⁺-doped germanate garnets have sufficiently high efficiency and persistence under electron beam excitation to be suitable for practical phosphor applications. The strontium yttrium germanate-Tb material has a cathodoluminescence decay time nearly three times that of the commercial P53 garnet phosphor.     

Time of flight mass spectrometry for quantitative data analysis in fast transient studies using a Temporal Analysis of Products (TAP) reactor

A Time of flight (ToF) mass spectrometer suitable in terms of sensitivity, detector response and time resolution, for application in fast transient Temporal Analysis of Products (TAP) kinetic catalyst characterization is reported. Technical difficulties associated with such application as well as the solutions implemented in terms of adaptations of the ToF apparatus are discussed. The performance of the ToF was validated and the full linearity of the specific detector over the full dynamic range was explored in order to ensure its applicability for the TAP application. The reported TAP-ToF setup is the first system that achieves the high level of sensitivity allowing monitoring of the full 0-200 AMU range simultaneously with sub-millisecond time resolution. In this new setup, the high sensitivity allows the use of low intensity pulses ensuring that transport through the reactor occurs in the Knudsen diffusion regime and that the data can, therefore, be fully analysed using the reported theoretical TAP models and data processing.     

Experimental and kinetic studies of the Escherichia coli glucuronylsynthase: an engineered enzyme for the synthesis of glucuronide conjugates

The detection and study of glucuronide metabolites is essential in many fields including pharmaceutical development, sports drug testing, and the detection of agricultural residues. Therefore, the development of improved methods for the synthesis of glucuronide conjugates is an important aim. The glycosynthase derived from E. coli β-glucuronidase provides an efficient, scalable, single-step synthesis of β-glucuronides under mild conditions. In this article we report on experimental and kinetic studies of the E. coli glucuronylsynthase, including the influence of acceptor substrate, pH, temperature, cosolvents, and detergents, leading to optimized conditions for glucuronide synthesis. Enzyme kinetics also reveals that both substrate and product inhibition may occur in glucuronylsynthase reactions but that these effects can be ameliorated through the judicious choice of acceptor and donor substrate concentrations. An investigation of temporary polar substituents was conducted leading to improved aqueous solubility of hydrophobic steroidal acceptors. In this way the synthesis of the steroidal metabolite dehydroepiandrosterone 3-β-D-glucuronide was achieved in three steps and 86% overall yield from dehydroepiandrosterone.     

Hypervelocity shock standoff on spheres in air

To provide data for the validation of computational fluid dynamics models, measurements of the shock standoff distance on spheres in hypervelocity flows have been made. Test flows of air at 8.7 and 9.7 km/s were generated in the X2 expansion tunnel fitted with a Mach 10 nozzle. High-speed video images were analysed with a least-squares shape-fitting algorithm. Assuming a spherical shock shape near the nose enabled increased resolution measurements beyond the native pixel size. Normalised shock standoff distances, $\Delta $ / $D$ , in the range 0.03–0.04 were measured, with sphere diameters, $D$ , of 40, 60 and 80 mm.     

Toward the Rationalization of Facilitated Hydrotropy: Investigation with the Ternary Dimethyl Isosorbide / Benzyl Alcohol / Water System

Solubility enhancement has been achieved by facilitated hydrotropy for the dimethyl isosorbide (DMI) / benzyl alcohol / water system. Facilitated hydrotropy has been studied via three different approaches: the solubilization in water of a hydrophobic dye, the evolution of the surface tension and dynamic light scattering, all as a function of the benzyl alcohol concentration. The facilitated hydrotropy has been rationalized from the solubilization properties of the system according to the ratio between the insoluble hydrotrope (here benzyl alcohol, a preservative used in parenteral injections) and the bio-sourced co-solvant (here the dimethyl isosorbide ether, DMI, a solvent used in pharmaceutical formulation). The presence of self-associated nanostructures has been detected by dynamic light scattering (DLS). It appears that the cosolvent, DMI, has an antagonistic action: DMI increases the facilitated hydrotrope (benzyl alcohol) solubility in the aqueous solution (favoring solute solubilization) but simultaneously decreases the hydrotropic efficiency of benzyl alcohol.     

Synthesis and Profiling of a Diverse Collection of Azetidine-Based Scaffolds for the Development of CNS-Focused Lead-like Libraries

The synthesis and diversification of a densely functionalized azetidine ring system to gain access to a wide variety of fused, bridged, and spirocyclic ring systems is described. The in vitro physicochemical and pharmacokinetic properties of representative library members are measured in order to evaluate the use of these scaffolds for the generation of lead-like molecules to be used in targeting the central nervous system. The solid-phase synthesis of a 1976-membered library of spirocyclic azetidines is also described.