Chemoenzymatic synthesis of optically active α-methylene-γ-carboxy-γ-lactams and γ-lactones

Three α-methylene-γ-carbomethoxy-γ-butyrolactams (methyl α-methylene-pyroglutamates) 11, 12 and 13, differing in the substitution at the heterocyclic nitrogen, as well as the structurally related γ-lactones 14 and 15 were synthesised and resolved enzymatically by hydrolysis of their ester function, mediated by commercially available hydrolytic enzymes. In particular, the α-chymotrypsin proved to be active to all the substrates examined, displaying a different degree of activity and enantioselectivity, this latter increasing significantly towards the substrate with an aromatic substituent at the nitrogen.     

Symmetry Properties of the Elastic Energy of a Woven Fabric with Bending and Twisting Resistance

A woven fabric can be described as a surface made of two families of fibers: in this work we study how the geometry of the weave pattern affects the symmetry properties of the elastic energy of the surface. Four basic symmetry classes of weave patterns are possible, depending on the angle between the fibers and their material properties. The properties of the pattern determine the material symmetry group of the network, under which the elastic energy is invariant. We derive representations for the energy of a woven fabric that are invariant under the symmetry group of the network, and discuss the relation of these invariants with the curvature and twist of the fibers.      

Noncovalent assembly of ferrocene on modified gold surfaces mediated by uracil–adenine base pairs

Redox-active ferrocene was assembled on gold surfaces through the hydrogen bonding interactions between adenine-substituted ferrocene and a uracil-terminated organothiol monolayer. The surface coverage of ferrocene Γ could be varied from ca. 4 × 10^? 11 to 2.0 × 10^? 10 mol cm^? 2 by diluting the thiol-modified uracil derivative with inert 1-octanethiol. A decrease in the apparent electron transfer rate constant for ferrocene, k_app, from ca. 50 to 10 s^? 1 was observed upon increasing Γ.     

Reaction of Ru3(CO)12 with but-2-yn-1,4-diol in CH3OH/KOH solution. Crystal structure of (μ-Cl)Ru3(CO)9[μ3-η-H2CCC(H)CH2]

The reaction of Ru₃(CO)₁₂ with but-2-yn-1,4-diol (HOCH₂CCCH₂OH, BUD) in CH₃OH/KOH followed by acidification with HCl leads to four products, one of which has been identified as the title complex (μ-Cl)Ru₃(CO)₉[μ₃-η⁴-H₂CCC(H)CH₂]. This is an open cluster containing a bridging Cl atom on the open side and a C₄H₅ moiety bound to all the metals. The structure of the complex has been determined by X-ray analysis.The thermal reaction of Ru₃(CO)₁₂ with BUD has been revisited for a comparison with the results in alkaline solution. The main product is the allylic derivative HRu₃(CO)₉[HCCHCCHO].     

Master chemotherapy planning and clinicians rostering in a hospital outpatient cancer centre

Central European Journal of Operations Research - In the past years, the number of patients in need of chemotherapy treatments has been constantly increasing. Chemotherapy treatments must be...     

Composite Polyamide 6/Polypyrrole Conductive Nanofibers

Conductive Polyamide 6 (PA‐6) nanofibers were prepared by making a conductive polypyrrole coating obtained by a polymerization of pyrrole molecules directly on the fiber surface. A solution of PA‐6 added with ferric chloride in formic acid has been electrospun and the fibers obtained showed an average diameter of 260 nm with a smooth surface. The fibers have been then exposed to pyrrole vapours and a compact coating of polypyrrole was formed on the fiber surface. The growth of the coating was monitored by measuring the increment of the fiber diameter and by FT‐IR spectroscopy. The same technique was used to study the interaction between the ferric chloride and the polyamide chains. The polypyrrole coating on the fibers turned out to be conductive with a pure resistive characteristic and the stability of the conductivity was evaluated in air at room temperature.

     

Quantitative determination of taurine in real samples by high-performance anion-exchange chromatography with integrated pulsed amperometric detection

As taurine is a very important compound involved in a large number of metabolic processes, it is naturally present in the mammal tissues and is often deliberately added in some foods as a fortifying component. A detailed knowledge of taurine metabolic roles in biological systems can be obtained only if a sensitive, reliable and rapid analytical method is available. This article describes the successful application of high-performance anion-exchange chromatography coupled with integrated pulsed amperometric detection (HPAEC-IPAD) for taurine determination in egg white and yolk samples, as well extracts of human serum and urine. Applications are shown for determination of taurine in soft drinks and pharmaceutical preparations where the taurine content was evaluated by standard additions. These results were achieved without prior derivatization of taurine.