Interaction-dependent PCR: identification of ligand-target pairs from libraries of ligands and libraries of targets in a single solution-phase experiment

Interaction-dependent PCR (IDPCR) is a solution-phase method to identify binding partners from combined libraries of small-molecule ligands and targets in a single experiment. Binding between DNA-linked targets and DNA-linked ligands induces formation of an extendable duplex. Extension links codes that identify the ligand and target into one selectively amplifiable DNA molecule. In a model selection, IDPCR resulted in the enrichment of DNA encoding all five known protein-ligand pairs out of 67?599 possible sequences.     

Dioxygenase-catalysed dihydroxylation of arene cis-dihydrodiols and acetonide derivatives: a new approach to the synthesis of enantiopure tetraoxygenated bioproducts from arenes

cis-Dihydrodiols of anthracene and benz[a]anthracene, and acetonide derivatives of the cis-dihydrodiols of benzene, fluorobenzene, biphenyl and phenanthrene have been identified as substrates for dioxygenase enzymes, yielding the corresponding enantiopure arene bioproducts, bis(cis-dihydrodiol)s and cis-diol acetonides respectively.     

In situ freezing point determination of cryolite baths utilising resistometer measurements

Now close to 30 years ago, Stephen Fletcher developed an instrument that measures uncompensated resistance simultaneously with electrochemical measurements and referred to that instrument as a “resistometer”. In this current work, the resistometer is modified to simultaneously measure the resistance (between the cathode and anode) and the capacitance (which is a combination of the interfacial capacitance of the cathode in series with the interfacial capacitance of the anode) in a Hall–Héroult simulator cell during cooling of a molten cryolite bath. A range of experiments with differing amounts of excess AlF₃ are carried out to investigate the effect on the freezing points of the bath. As the bath cools through different freezing events (of the multiple components of the bath), the resistance increases and the capacitance decreases giving valuable information about the freezing behaviour of different compositions of cryolite melts, which has implications for low temperature melts and the investigation of the frozen ledge behaviour in Hall–Héroult cells.     

Synthesis and structure of the first per-substituted anthracene host: decakis(cyclopentylthio)anthracene

Abstract

The title compound, a novel host molecule, has been prepared both from mixtures of unsaturated fluorocarbons related to perfluoro-perhydroanthracene and, in an extension of a remarkable new reaction, perfluoroperhydroanthracene itself. The 1,4-dioxane inclusion compound of this anthracene-based host is triclinic, space group P 1, with a = 11.826(1), b = 15.297(1), c = 20.280(1) Å, α = 98.77(1), β = 99.85(1), and γ = 95.83(1)°, with two host, and ca. three 1,4-dioxane guest molecules per unit cell. The host molecule occupies a general position in the unit cell and its anthracene core is markedly non-planar; each of the three crystallographically independent six-membered rings possesses a shallow twist-boat conformation. The host's side-chain moieties display an asymmetrical conformational distribution of the abbabaabab type (a = above, b = below, mean core plane).     

A simple model for a two-stage chemical reaction with diffusion

We analyse the evolution of a two-stage chemical reaction betweentwo neighbouring plumes of reactants. Under the assumption thatthe plumes are approximately Gaussian we derive a system ofordinary differential equations for the total amount, the centroidand the variance of each reactant. We compare the solution ofthese equations with full numerical simulation of the reaction.Excellent agreement is obtained, with solution of the near-Gaussianmodel requiring considerably less computational effort thanthe full simulations. Of key importance is the yield of thereaction, and we discuss this feature in particular.     

Ultra resolution chemical fingerprinting of dense non-aqueous phase liquids from manufactured gas plants by reversed phase comprehensive two-dimensional gas chromatography

Ultra resolution chemical fingerprinting of dense non-aqueous phase liquids (DNAPLs) from former manufactured gas plants (FMGPs) was investigated using comprehensive two-dimensional gas chromatography coupled with time of flight mass spectrometry (GC×GC TOFMS). Reversed phase GC×GC (i.e. a polar primary column coupled to a non-polar secondary column) was found to significantly improve the separation of polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues. Sample extraction and cleanup was performed simultaneously using accelerated solvent extraction (ASE), with recovery rates between 76% and 97%, allowing fast, efficient extraction with minimal solvent consumption. Principal component analysis (PCA) of the GC×GC data was performed in an attempt to differentiate between twelve DNAPLs based on their chemical composition. Correlations were discovered between DNAPL composition and historic manufacturing processes used at different FMGP sites. Traditional chemical fingerprinting methods generally follow a tiered approach with sample analysis on several different instruments. We propose ultra resolution chemical fingerprinting as a fast, accurate and precise method of obtaining more chemical information than traditional tiered approaches while using only a single analytical technique.     

The EPR Spectrum of Di-μ-(pyridine N-oxide) bis [bisnitrato(pyridine N-oxide)copper(II)] in the Corresponding Zinc(II) Crystal

It has been shown^1–3 that the exchange interactions in the dimeric⁴ complex di-μ-(pyridine N-oxide) bis [bisnitrato(pyridine N-oxide) copper(II)], [Cu(pyO)₂]₂ lead to a triplet ground state for the copper(II) pairs. The triplet state epr spectrum has been observed^1,3,5,6 for a powdered sample of the complex coprecipitated with the corresponding zinc(II) complex, and the computer simulation of this spectrum has been carried out by two different groups^3,5,6. As is often the case when dealing with spectra of powdered samples, there exist ambiguities with the spectrum of [Cu(pyO)₂-(NO₃)₂]₂ since all of the resonances were not observed, and consequently, the interpretation and values of the parameters remain in question. It was felt that examination of the epr spectra of single crystal samples should permit a rigorous analysis of this problem.     

Imaging cytoplasmic cAMP in mouse brainstem neurons

Background  

cAMP is an ubiquitous second messenger mediating various neuronal functions, often as a consequence of increased intracellular Ca²⁺ levels. While imaging of calcium is commonly used in neuroscience applications, probing for cAMP levels has not yet been performed in living vertebrate neuronal tissue before.     

Laser-induced thermomigration of Te precipitates in CdZnTe crystals

The thermomigration of tellurium precipitates in a cadmium zinc telluride (CdZnTe) crystal was observed using an infrared (IR) CO₂ laser beam. Te precipitates present in CdZnTe have been shown to thermally migrate along a temperature gradient. Selective energy deposition from an IR laser beam in Te precipitates was investigated as a potentially advantageous approach to speed the annealing of Te precipitates in CdZnTe. Initial results indicate Te precipitates do thermally migrate under IR laser heating.