The structures and properties of tetrafluoromethane, hexafluoroethane, and octafluoropropane using the AIMPRO density functional program

The AIMPRO density functional program was used to calculate the structures and properties of the three simplest perfluoroalkanes: tetrafluoromethane, hexafluoroethane, and octafluoropropane. The method reproduces both the molecular structures and the vibrational spectra well, and in addition, has identified a new C₂-symmetry ortho-conformer of octafluoropropane that is approximately 0.525 kcal/mol (2.20 kJ/mol) higher in energy than the well-known C_2v-symmetry global minimum staggered-conformer.     

Electrowetting of superhydrophobic ZnO nanorods

This paper reports the electrowetting properties of ZnO nanorods. These nanorods were grown on indium tin oxide (ITO) substrates using different liquid-phase deposition techniques and hydrophobized with sputtered Teflon. The surfaces display superhydrophobic properties. When the applied voltages are less than 35 V, the contact angle change is small and exhibits instant reversibility. For higher voltages, larger contact angle changes were observed. However, the surface was not reversible after removing the applied voltage and required mechanical agitation to return to its initial superhydrophobic state.     

Two polymorphs of bis(1,10‐phenanthroline‐κ2N,N′)copper(I) iodide

The title complex, [Cu(C₁₂H₈N₂)₂]I, (I), has been crystallized in two polymorphic forms, both containing four‐coordinate copper. Both forms are orthorhombic, with form (Ia) crystallizing in the primitive space group Pban and form (Ib) in the c‐centred space group Ccca. In (Ia), the complex cation and the I⁻ anion both have 222 crystallographic symmetry, and in (Ib), the complex cation has approximate 222 symmetry, with the I⁻ counter‐ion distributed over three special positions.     

Nanoporous WO3 from anodized RF sputtered tungsten thin films

We report the first electrochemical anodization of RF (radio-frequency) sputtered tungsten (W) thin films. High pressure sputtering was utilized to produce W films of low intrinsic stress with a high degree of adhesion to the transparent substrates. Structurally and uniformly porous tungsten trioxide (WO₃) films were obtained under optimised anodization conditions in fluoride ion-containing electrolyte. Crystalline WO₃ was obtained after annealing the films at 450 °C. SEM and XRD characterisation techniques were used to determine the surface morphology and crystal structure of the non-anodized and anodized films.     

Testing inflation: a bootstrap approach

We note that the essential idea of inflation, that the Universe underwent a brief period of accelerated expansion followed by a long period of decelerated expansion, can be encapsulated in a "closure condition" which relates the amount of accelerated expansion during inflation to the amount of decelerated expansion afterward. We present a protocol for systematically testing the validity of this condition observationally.     

Lumped parameter model for multimode laser cutting

A lumped parameter mathematical model is developed to relate the cut depth to the laser cutting parameters and material properties. The model takes into account the threshold power of the incident laser beam for the initiation of cutting and modifies an earlier cutting model so that it applies to a wide set of process parameters ranging from low to high laser powers and slow to fast cutting speeds. Plain steel is taken as an example to show the effects of various process parameters such as the laser power, spot size and cutting speed on the cut depth. Special emphasis is given to the effect of laser mode structure on its cutting capability.     

The interaction of high- and low-frequency waves in a free electronlaser

When a free electron laser (FEL) interaction occurs inside a waveguide, there are two possible operating frequencies at the two intersections of the beam line with the waveguide dispersion curve. Using a one-dimensional model valid for a low-gain oscillator, the mode competition between the high- and low-frequency waves is studied. It is found that the low-frequency wave can be nonlinearly suppressed, even when its linear growth rate is positive. When the frequency ratio is two, phase locking occurs and the nonlinear gain of the low-frequency wave can exceed its linear growth rate     

Synthesis of 1,2,3-triazolo[1,5-a]pyridine ester derivatives

Lithiation of 1,2,3-triazolo[1,5-a]pyridines 4b and 4c with lithium diisopropylamide (LDA) gave the corresponding lithio derivatives 5b and 5c from which esters 6b and 6c were obtained by treatment with carbon dioxide and then dimethyl sulfate. Lithio derivatives 5a-5c reacted with DMF giving aldehydes 7a-7c. Esters 9a-9c were prepared from aldehydes 7a-7c and carbomethoxymethylenetriphenylphosphorane.