Thin films of polymer mimics of cross-linking mussel adhesive proteins deposited by matrix assisted pulsed laser evaporation

Mussels secrete specialized adhesives known as mussel adhesive proteins, which allow attachment of the organisms to underwater marine environments. Obtaining large quantities of naturally derived mussel adhesive proteins adhesives has proven to date rather problematic, thus, synthetic analogs of mussel adhesive proteins have recently been developed. We report deposition of 1:100 and 1:1000 poly[(3,4-dihydroxystyrene)-co-styrene)] mussel adhesive protein analogs by matrix assisted pulsed laser evaporation (MAPLE) using an ArF* excimer laser source. The deposited films have been evaluated for their antifouling behavior. The MAPLE-deposited synthetic mussel adhesive protein analog thin films are homogenous and adhesive, making the use of these materials in thin film form a viable option.     

GC-FID as a primary method for establishing the purity of organic CRMs used for drugs in sport analysis

The National Analytical Reference Laboratory has synthesized and characterized 67 anabolic steroid marker metabolites, both unlabelled and deuterated, and 37 key glucuronide and sulfate steroid conjugate pure substance reference materials. Work is also in process to establish their full traceability so that they can be issued as certified and primary reference materials. Both identity and purity have been rigorously characterized using a number of techniques and a primary method for purity assessment developed, based gas chromatography combined with flame ionization detection for the parent steroids and HPLC with evaporative light scattering detection for non-volatile steroid conjugates. Strategies for establishing traceability and for estimating measurement uncertainty are reported. The strategies described are considered applicable to a wide range of organic pure substance reference materials.     

Polycyclic ethers and an unexpected dearomatisation reaction during studies towards the bioactive alkaloid,perophoramidine

The bioactive alkaloid natural product perophoramidine and the related family of compounds known as the communesins have inspired the synthesis community for more than a decade. Many of the elegant approaches have required the synthesis of complex intermediates that have not always reacted in the expected manner. In this study we describe a series of cyclic ether-containing precursors that were prepared during our synthetic studies towards these natural products. Attempts to open the cyclic ether ring and trap the resulting stabilised carbocation with a carbon nucleophile ultimately led to the preparation of a diallyl-substituted all carbon quaternary centre. Subsequent attempts to differentiate between the two allyl groups resulted in a relatively clean transformation to an unexpected compound. Extensive structural characterisation, including small molecule X-ray crystallography, showed that a dearomatisation reaction had occurred.     

Critical petermann K factor for intensity noise squeezing

We investigate the impact of the Petermann-excess-noise factor K>/=1 on the possibility of intensity noise squeezing of laser light below the standard quantum limit. Using an N-mode model, we show that squeezing is limited to a floor level of 2(K-1) times the shot noise limit. Thus, even a modest Petermann factor significantly impedes squeezing, which becomes impossible when K>/=1.5. This appears as a serious limitation for obtaining sub-shot-noise light from practical semiconductor lasers. We present experimental evidence for our theory.     

An improved understanding of the reaction of bis(bromomethyl)quinoxaline 1-N-oxides with amines using substituent effects

The reaction of bis(bromomethyl)quinoxaline N-oxides with amines is interesting from a reaction mechanism perspective and due to the reported biological activity of compounds in this general class. The complex mechanism of this reaction (particularly in the case of primary amines) is complicated further when C6 or C7 substituted mono-N-oxides are considered. In this study, the synthesis and subsequent characterization of a series of 2,3-bis(bromomethyl)quinoxaline 1-N-oxides is reported. Experimental and computational evidence is used to show that the observed product ratios from the reaction with diethylamine reflect the influence of both the C6/C7 substituent and the N-oxide functional group on the initial nucleophilic substitution reaction.