Synthesis of trans-(3S,4S)-dibenzyloxycyclopentanone

The 1-cyano-1-thiophenylcyclopentone derivative $\text{1}$, obtained from (R,R)-(+)-tartaric acid, has been converted into a number of derivatives including the important $\text{trans}$-(3S,4S)-dibenzyloxycyclopentanone $\text{2}$ in 45% overall yield.     

Efficiency of preparative and process column distribution systems

An analytical method for computing the residence time distribution of the liquid distribution system in chromatography columns is described. The impact of the distributor design on the separation efficiency is predicted as a function of media properties and packed bed dimensions. The efficiency loss due to the distributor when increasing column diameter during scale-up is quantified. It is shown that this loss can be compensated by modulating the local bed height via a moderate inclination of the bed support. It is concluded that the selection of an appropriate distributor design concept with optimised dimensions enables a scale-up of chromatographic separations without any significant loss of chromatographic efficiency due to the distribution system.     

Synthesis of compounds of interest in proton transfer spectroscopy

A new series of compounds has been prepared for use in proton transfer spectroscopy. The complexes 6a-6d have been converted into the fully characterised perchlorates 7a-7d and the corresponding anhydro bases 8a-8d.     

How covariant closed string theory solves a minimal area problem

For a given genusg Riemann surface withn0 punctures (n3 forg=0) we consider the problem of finding the metric of minimal area under the condition that the length of any nontrivial closed curve be greater or equal to 2. The minimal area metrics are found for the case of all punctured genus zero surfaces and for many of the higher genus surfaces both with and without punctures. These metrics are induced by Jenkins-Strebel quadratic differentials. They arise from the string diagrams corresponding to restricted Feynman graphs of a closed string field theory action containing classical and quantum restricted polyhedra.Supported in part by funds provided by the U.S. Department of Energy (D.O.E.) under contract #DE-AC02-76ER03069     

Molecular imaging by Mid-IR laser ablation mass spectrometry

Mid-IR laser ablation at atmospheric pressure (AP) produces a mixture of ions, neutrals, clusters, and particles with a size distribution extending into the nanoparticle range. Using external electric fields the ions can be extracted and sampled by a mass spectrometer. In AP infrared (IR) matrix-assisted laser desorption ionization (MALDI) experiments, the plume was shown to contain an appreciable proportion of ionic components that reflected the composition of the ablated target and enabled mass spectrometric analysis. The detected ion intensities rapidly declined with increasing distance of sampling from the ablated surface to ∼4 mm. This was rationalized in terms of ion recombination and the stopping of the plume expansion by the background gas. In laser ablation electrospray ionization (LAESI) experiments, the ablation plume was intercepted by an electrospray. The neutral particles in the plume were ionized by the charged droplets in the spray and enabled the detection of large molecules (up to 66 kDa). Maximum ion production in LAESI was observed at large (∼15 mm) spray axis to ablated surface distance indicating a radically different ion formation mechanism compared to AP IR-MALDI. The feasibility of molecular imaging by both AP IR-MALDI and LAESI was demonstrated on targets with mock patterns. Presented at the 9-th International Conference on Laser Ablation, 2007 Tenerife, Canary Islands, Spain     

Sequestering perrhenate with a borate-based coordination polymer: a model for pertechnetate separation

Crystals of the layered metal organic framework solid Pb[B(Im)4](NO3)(nH2O) can undergo exchange of the nitrate for perrhenate, a model for pertechnetate, forming Pb[B(Im)4](ReO4). We can monitor this reaction by 207Pb solid-state NMR and can isolate single crystals of the resultant material through growth in the presence of an excess of perrhenate. Such a synthetic metal-organic framework solid represents a new candidate for pertechnetate-sequestering materials.     

Pseudorapidity and centrality dependence of the collective flow of charged particles in Au+Au collisions at sqrt[s(NN)]=130 GeV

This paper describes the measurement of collective flow for charged particles in Au+Au collisions at sqrt[s(NN)]=130 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). The measured azimuthal hit anisotropy is presented over a wide range of pseudorapidity (-5.0相似文献   

Two iridanonaborane compounds

Two iridanonaborane compounds, 4-carbonyl-5,6:8,9-bis-μH-4-hydrido-4-bis­(tri­methyl­phosphine)-4-irida-arachno-nonaborane(12), [IrH(B₈H₁₂)(C₃H₉P)₂(CO)], (Ia), and 2-carbonyl-2,5:6,9:8,9-tri-μH-4-chloro-2-bis­(tri­methyl­phosphine)-2-irida-nido-nonaborane(11), [Ir(B₈H₁₀Cl)(C₃H₉P)₂(CO)], (II), are described. Compound (II) shows evidence of effective chlorine-substituent migration during its formation.