Gas‐flow assisted ion transfer for mass spectrometry

Methods and devices that use gas flows to collect ions and transfer them over long distances for mass spectrometric analysis have been developed. Gas flows derived from the ionization source itself or provided by means of additional pumping were used to generate a laminar flow inside cylindrical tube. Hydrodynamic simulations and experimental tests demonstrate that laminar flow can transfer ions over long distance. The typical angular discrimination effects encountered when sampling ions from ambient ionization sources are minimized, and the sampling of relatively large surface areas is demonstrated with desorption electrospray ionization (DESI). Ion transfer over 6 m has been achieved and its application to multiplexed chemical analysis is demonstrated on samples at locations remote from the mass spectrometer. Copyright © 2012 John Wiley & Sons, Ltd.     

Photochemically Cross‐linked Poly(aryl ether ketone) Rings

Summary: Macrocyclic phenyl ether ketones were prepared via pseudo high dilution condensation. Irradiation of these rings with UV light in a solution containing isopropyl alcohol as hydrogen donor resulted in a photo‐induced reduction of benzophenone to benzopinacol and the formation linked macrocycles. These rings can be heated to undergo ring‐opening polymerization and produce a polymer network or they can be added to a polycondensation reaction to prepare poly(ether ether ketones) with variable degrees of cross‐linking.

Photochemical cross‐linking of PEK rings and ring opening polymerization (n: 2–6). (a) hν, iPrOH, DCM; (b) CsF, 260 °C (polymer 3 ); (c) 4,4′–difluorobenzophenone, hydroquinone, diphenylsulphone, K₂CO₃, 260 °C (2% polymer 4 ; 6% polymer 5 ).     

Macroscopic and microscopic properties of solutions of aromatic compounds in an ionic liquid

Molecular dynamics simulations of binary mixtures of benzene, 1,3,5-trifluorobenzene and hexafluorobenzene with dimethylimidazolium hexafluorophosphate were carried out to examine their macroscopic and microscopic properties. The energies and volumes of mixing of these mixtures correlate well with observed microscopic properties including coordination number about the aromatic compound. The local ordering of the ions about an aromatic molecule was found to depend on the quadrupole moment of the aromatic species and to remain qualitatively the same on varying the mole fraction of the aromatic species. Interaction energies showed the most significant interactions to be between the aromatic molecule and the ions located about its equator. These findings have implications for the practical use of ionic liquids as solvents for chemical processes.     

Large antichains in the partition lattice

Consider the partially ordered set of all partitions of an n-element set, ordered by refinement. The sizes of the various ranks within this poset are the Stirling numbers of the second kind. We show that the ratio of the size of the largest antichain to the size of the largest rank exceeds n^1/35 for all n sufficiently large.     

Co-H-maps to spheres

Criteria are given which characterize Co-H and Co-A maps from arbitrary double suspensions to odd dimensional spheres in terms of the maps in the EHP sequence.     

The synthesis of some bidentate ligands containing both phosphine and nitrile groups

Both (C₆H₅)₂P(CH₂)₃CN and (C₆H₅)₂P(CH₂)₄CN have been obtained from the reaction of Br(CH₂)_nCN (n = 3, 4) with (C₆H₅)₂POCH₃ followed by reduction with (C₆H₅)₂SiH₂. These phosphine-nitrile ligands form L₂PdCl₂ complexes which are shown by IR measurements to have trans geometries with the phosphine portions of the ligands coordinated. Reactions of o-BrC₆H₄CN with CH₃(CH₂)₃Li followed by R₂PCl (R = C₆H₅ or (CH₃)₂N) have been used to provide good yields of the corresponding R₂P-o-C₆H₄CN products.     

Controlled composting of straw

Production of composts on the farm from surplus straw might provide a low-cost biotechnological approach for increasing the value of this lignocellulosic waste. Successful composting depends on the conversion of the polysaccharides (cellulose and hemicelluloses) of straw by inoculated microorganisms to products that can promote plant growth when applied to the land. None of the potentially useful products we have identified are produced by cellulolytic organisms. We have therefore studied mixed populations in which noncellulolytic bacteria depend for growth on the products of fungal cellulolysis. The nature and yield of bacterial products depends not only on conditions within the compost, but also on the microbial inoculants used. Under defined laboratory conditions, using pure cellulose, N₂ is fixed by the anaerobic bacteriumClostridium butyricum in association with a cellulolytic fungus such asTrichoderma sp. A similar association has been achieved on straw withPenicillium corylophilum as the cellulolytic fungus. Cellulolytic fungi can also provide available substrates for the production of bacterial polysaccharides that can improve the structure of unstable soils. The yield of polysaccharide and its efficacy in soil aggregate stabilization again varies with the inoculants used. Such composts can thus contribute to plant nutrition and to soil structure. The adoption ofTrichoderma spp. as the cellulolytic inoculants would further extend the potential value of the compost to include the biocontrol of plant pathogens.     

Electroaddressable Selective Functionalization of Electrode Arrays: Catalytic NADH Detection Using Aryl Diazonium Modified Gold Electrodes

We report the application of 4‐nitrophenyl diazonium modified electrodes towards the electrochemical detection of NADH. Selective activation of individual electrodes on a 5 element array by electro‐addressable conversion of nitro groups to amines and subsequent EDC/NHS crosslinking to the NADH oxidant, pyrroloquinoline quinone (PQQ), is demonstrated. Inactivated electrodes retained nitro functionality and were protected against non‐specific adsorption and mild chemical reactions. Electrodeposition conditions were used to control nitrophenyl film thickness and showed that while increased film thickness leads to greater functionalization density of PQQ, it also results in decreased electron transfer kinetics. The electrodeposition protocol can therefore serve as a method to control electrode functionalization density and film electron transfer kinetics. We believe this simple technique for selective electrode functionalization may facilitate the development of next generation multianalyte electrochemical sensors.