Structural and Electronic Control of the Bidentate 1-(2-pyridyl)benzotriazole Ligand in Copper Chemistry with Application to Catalysis in the A3 Coupling Reaction

The hybrid bidentate 1-(2-pyridyl)benzotriazole (pyb) ligand was introduced into 3d transition metal catalysis. Specifically, [Cu^II(OTf)₂(pyb)₂] ⋅ 2 CH₃CN ( 1 ) enables the synthesis of a wide range of propargylamines by the A³ coupling reaction at room temperature in the absence of additives. Experimental and high-level theoretical calculations suggest that the bridging N atom of the ligand imposes exclusive trans coordination at Cu and allows ligand rotation, while the N atom of the pyridine group modulates charge distribution and flux, and thus orchestrates structural and electronic precatalyst control permitting alkyne binding with simultaneous activation of the C−H bond via a transient Cu^I species.     

Economical,Green, and Safe Route Towards Substituted Lactones by Anodic Generation of Oxycarbonyl Radicals

A new electrochemical methodology has been developed for the generation of oxycarbonyl radicals under mild and green conditions from readily available hemioxalate salts. Mono‐ and multi‐functionalised γ‐butyrolactones were synthesised through exo‐cyclisation of these oxycarbonyl radicals with an alkene, followed by the sp³–sp³ capture of the newly formed carbon‐centred radical. The synthesis of functionalised valerolactone derivatives was also achieved, demonstrating the versatility of the newly developed methodology. This represents a viable synthetic route towards pharmaceutically important fragments and further demonstrates the practicality of electrosynthesis as a green and economical method to activate small organic molecules.     

Simulating the Work of a Tendering Technical Company

Preparing tenders usually requires the technical staff who would otherwise be preparing manufacturing drawings for products that have been ordered. Work that will be paid for and work that may not be paid for are thus competing for the same resources. Tendering is essential, however, in the type of company discussed, because it is the successful tenders which generate future company revenue.The simulation explores the allocation of technical resources to tendering and the problem is seen to have something in common with job shop scheduling. There is, however, the additional complication that, since a tender is likely to be unsuccessful, the complete number of activities and costs cannot be predicted.It is found that, if we attempt to load a technical department so heavily that a man is required to work more than about 80% of his available time, unacceptably long job turn-round times are created. Long turn-round times reduce the probabilities of tenders generating orders.Increasing the design effort spent on tenders eventually has a bad effect, ending in reduced numbers of orders.It is necessary for the manager to refuse work when the system is overloaded.     

Two Diophantine Birds with One Stone

Integer Solutions are found to the equations t²–3(a²,b², (a + b)², (a–b)²) = p², q², r², s². These lead surprisinglyto solutions to the equations u² + (c², d², (c + d)², (c –d)²) = p², q², v², w², with the same values of p and q.     

The application of a hypothesis-driven strategy to the sensitive detection and location of acetylated lysine residues

The application of a hypothesis-driven method for the sensitive determination of lysine acetylation sites on enzymatically digested proteins is described. Comparative sensitivity tests were carried out using serial dilution of an acetylated bovine serum albumin (AcBSA) digest to assess the performance of a multiple reaction monitoring (MRM)-based approach as compared to a more conventional precursor scanning (PS) method. Both methods were capable of selectively detecting an acetylated peptide at the low femtomole level when spiked into a background of 500 fmol six-protein tryptic digest. The MRM approach was roughly tenfold more sensitive than precursor scanning with one acetylated peptide detected and sequenced at the level of 2 fmol on-column. The technique was subsequently applied to a gel-derived sample of cytokeratin-8 (CK8) shown to contain acetylated lysine residues by Western blot analysis. The strategy applied herein, termed MRM-initiated detection and sequencing (MIDAS), resulted in the facile identification of novel sites of acetylation on this protein.     

FEM analysis on mixed-mode fracture of CSM-GRP

A FEM analysis for studying mixed-mode fracture problem of chopped strand mat glass fibre reinforced polyester laminate is presented. The analysis is formulated on the basis of 8-node quadrilateral isoparametric element. The collapsed triangular quarter-point singular elements were used for calculating stress intensity factors K_Ι and K_Ⅱ.The crack propagation process was computed by implementing constraint release technique. Three different approaches to the solution of stress intensity factors K_Ι and K_Ⅱ were compared. The effect of constraint condition imposed upon the displacement of the three collapsed nodes of the crack tip elements on the K_Ι and K_Ⅱ results was evaluated. The mixed-mode critical stress intensity factors K_ΙC and K_ⅡC were estimated for CSM-GRP through the consideration of K_Ι and K_Ⅱ calculated and the measured failure load and critical crack length in the experiment.     

Charge transport through Geobacter sulfurreducens biofilms grown on graphite rods

Biofilms of the electroactive bacterium Geobacter sulfurreducens were induced to grow on graphite-rod electrodes under a potential of 0 V (vs Ag/AgCl) in the presence of acetate as an electron donor. Increased anodic currents for bioelectrocatalytic oxidation of acetate were obtained when the electrodes were incubated for longer periods with periodic electron-donor feeding. The maximum current density for acetate oxidation increased 2.8-fold, and the biofilm thickness increased by 4.25-fold, over a time period of 83-147 h. Cyclic voltammetry in the presence of acetate supports a model of heterogeneous electron transfer, one electron at time, from biofilm to electrode through a dominant redox species centered at -0.41 V vs Ag/AgCl. Voltammetry performed under nonturnover conditions provided an estimate of the surface coverage of the redox species of 25 nmol/cm(2). This value was used to estimate a redox species concentration of 7.3 mM within the 34-μm-thick biofilm and a charge-transport diffusion coefficient of 3.6 × 10(-7) cm(2)/s. This value of diffusion coefficient is greater than that observed in traditional thin-film voltammetric studies with redox polymer films containing much higher surface concentrations of redox species and might be associated with proton transport to ensure electroneutrality within the biofilm upon electrolysis.     

Mediated electron transfer of cellobiose dehydrogenase and glucose oxidase at osmium polymer-modified nanoporous gold electrodes

Nanoporous and planar gold electrodes were utilised as supports for the redox enzymes Aspergillus niger glucose oxidase (GOx) and Corynascus thermophilus cellobiose dehydrogenase (CtCDH). Electrodes modified with hydrogels containing enzyme, Os-redox polymers and the cross-linking agent poly(ethylene glycol)diglycidyl ether were used as biosensors for the determination of glucose and lactose. Limits of detection of 6.0 (±0.4), 16.0 (±0.1) and 2.0 (±0.1) μM were obtained for CtCDH-modified lactose and glucose biosensors and GOx-modified glucose biosensors, respectively, at nanoporous gold electrodes. Biofuel cells composed of GOx- and CtCDH-modified gold electrodes were utilised as anodes, together with Myrothecium verrucaria bilirubin oxidase (MvBOD) or Melanocarpus albomyces laccase as cathodes, in biofuel cells. A maximum power density of 41 μW/cm² was obtained for a CtCDH/MvBOD biofuel cell in 5 mM lactose and O₂-saturated buffer (pH 7.4, 0.1 M phosphate, 150 mM NaCl).     

Computer simulation of the trajectories of large water jets

A three-dimensional computer simulation of the motion of a water jet is described which includes the effects of wind from any direction. The simulation is useful in the design of fire-fighting systems, particularly those used in offshore situations. The equations of motion are presented in vector form and the problem of the fluid dynamic drag variation is discussed. Semi-empirical approximations for the drag components along and across the jet are presented which involve four unknown constants. These are reduced to three by using previous data on the efficiency of vertical jets. To fix the remaining constants, information was available from a series of large jets tests carried out to prove an offshore fire fighting system. In these tests different nozzle shapes were tried and, using the best of these shapes, a large number of trajectories were measured photographically. These were used to fix the simulation drag constants and good agreement is shown between measurements and predictions. The simulation enables the effects of flow-rate, pressure, nozzle size, elevation and wind strength to be evaluated in the system design