Thermal and microwave-assisted N-formylation using solid-supported reagents

A rapid and easy route to formamides by microwave assisted N-formylation of primary and secondary amines is described. Using an insoluble polymer or an inorganic solid-supported reagent as a formylating agent, microwave irradiation furnished the corresponding formamides in high yields, with reduced reaction time and solvent volume over the conventional approach.     

Ligand discrimination in the reaction of nitrones with [PtCl2(PhCN)2]. Selective formation of mono-oxadiazoline and mixed bis-oxadiazoline complexes under thermal and microwave conditions

[2+3] Cycloaddition of nitrones to the nitrile ligands in the complexes cis- or trans-[PtCl2(PhCN)2] occurs under ligand differentiation and allows for selective synthesis of complexes of the type cis- or trans-[PtCl2(oxadiazoline)(PhCN)]. Microwave irradiation enhances the reaction rates of the cycloaddition considerably and further favours the selectivity towards the mono-cycloadduct with respect to thermal conditions, because the first cycloaddition is accelerated to a higher extent than the second one. Reaction of the trans-substituted mono-oxadiazoline complexes with a nitrone different from the one used for the first cycloaddition step gives access to mixed bis-oxadiazoline compounds of the composition trans-[PtCl2(oxadiazoline-a)(oxadiazoline-b)]. The corresponding cis-configured complexes, however, do not undergo further cycloaddition. All reactions described occur without isomerisation of the stereochemistry around the platinum center, independently of whether thermal or microwave heating is applied.     

The chemistry of (1-azabuta-1,3-diene)tricarbonyliron(0) complexes

In this review, an overview of synthetic and structural aspects of 1-azabuta-1,3-diene complexes of iron is given and the reactivity of these complexes is discussed with regard to inorganic, organometallic, organic and stereochemical aspects of their chemistry. Their application in the synthesis of organic and organometallic target compounds, or as transfer reagents of the tricarbonlyiron(0) moiety is demonstrated.     

Towards conformationally dependent redox-responsive molecular switches. New polyferrocene bis benzo crown ether receptors

New polyferrocene bis benzo-15-crown-5 ligands have been prepared and shown to form 1:1 intramolecular sandwich complexes with the potassium cation. Electrochemical investigations reveal that both receptors undergo small anodic perturbations of the respective ferrocene-ferrocenium redox couples in the presence of alkali metal cations.     

A bioinformatics approach to the development of immunoassays for specified risk material in canned meat products

A bioinformatics approach to developing antibodies to specific proteins has been evaluated for the production of antibodies to heat-processed specified risk tissues from ruminants (brain and eye tissue). The approach involved the identification of proteins specific to ruminant tissues by interrogation of the annotation fields within the Swissprot database. These protein sequences were then interrogated for peptide sequences that were unique to the protein. Peptides were selected that met these criteria as close as possible and that were also theoretically resistant to either pepsin or trypsin. The selected peptides were synthesised and used as immunogens to raise monoclonal antibodies. Antibodies specific for the synthetic peptides were raised to half of the selected peptides. These antibodies have each been incorporated into a competitive enzyme-linked immunosorbent assay (ELISA) and shown to be able to detect the heat-processed parent protein after digestion with either pepsin or trypsin. One antibody, specific for alpha crystallin peptide (from bovine eye tissue), was able to detect the peptide in canned meat products spiked with 10% eye tissue. These results, although preliminary in nature, show that bioinformatics in conjunction with enzyme digestion can be used to develop ELISA for proteins in high-temperature processed foods and demonstrate that the approach is worth further study.     

Potassium selective chromoionophores

The ionisable chromoionophores5 were synthesised from simple precursors. These chromoionophores extract alkali metal cations from aqueous solutions at pH > 7 into dichloromethane. The ratio of extraction coefficients for the chromoionophore5c for K⁺ and Na⁺ indicate that it has potential for use in optical fibre sensors for K⁺ in the presence of Na⁺, Mg²⁺ and Ca²⁺ at extracellular concentrations.This paper is dedicated to the memory of the late Dr C. J. Pedersen.     

Wisdom of crowds versus groupthink: learning in groups and in isolation

We evaluate the asymptotic performance of boundedly-rational strategies in multi-armed bandit problems, where performance is measured in terms of the tendency (in the limit) to play optimal actions in either (i) isolation or (ii) networks of other learners. We show that, for many strategies commonly employed in economics, psychology, and machine learning, performance in isolation and performance in networks are essentially unrelated. Our results suggest that the performance of various, common boundedly-rational strategies depends crucially upon the social context (if any) in which such strategies are to be employed.     

Driving matrix liquid crystal displays

Liquid crystal displays had a humble beginning with wrist watches in the seventies. Continued research and development in this multi-disciplinary field have resulted in displays with increased size and complexity. After three decades of growth in performance, LCDs now offer a formidable challenge to the cathode ray tubes (CRT). A major contribution to the growth of LCD technology has come from the developments in addressing techniques used for driving matrix LCDs. There are several approaches like passive matrix addressing, active matrix addressing and plasma addressing to drive a matrix display. Passive matrix LCD has a simple construction and uses the intrinsic non-linear characteristic of the LCD for driving. Departure from conventional line by line addressing of a passive matrix has resulted in improved performance of the display. Orthogonal functions have played a crucial role in the development of passive matrix addressing. Simple orthogonal functions that are useful for driving a matrix LCD are introduced. The basics of driving several rows simultaneously (multi-line addressing) are discussed by drawing analogies from multiplexing in communication. The impact of multi-line addressing techniques on the performance of the passive matrix LCDs in comparison with the conventional technique will be discussed.