Absolute triple differential cross-section measurements in energy sharing kinematics and a coplanar asymmetric geometry at 100 and 200 eV on He

Results of measurements for electron impact ionization of atomic helium are reported for energy-sharing kinematics in a coplanar asymmetric geometry. Incident energies of 100 eV and 200 eV are considered and comparison with previous experiments in fully symmetric kinematics allows the results to be put on an absolute scale. The cross-sections are compared with those obtained from two variants of the distorted wave Born approximation (DWBA) model. Good general agreement is obtained for the form of the angular distributions. The absolute magnitude of the cross sections is however not compatible with the choice of half-on-shell Coulomb T-Matrix currently used in the distorted wave impulse and related approximations.     

Investigating Electrochemical Stability and Reliability of Gold Electrode‐electrolyte Systems to Develop Bioelectronic Nose Using Insect Olfactory Receptor

This article aims to demonstrate an electrochemically stable and reliable gold electrode‐electrolyte system to develop an insect odorant receptor (Drosophila melanogaster Or35a) based bioelectronic nose. Cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS) of bare gold electrodes, after modification with the self‐assembled monolayer (SAM) of 6‐mercaptohexanoic acid (MHA) and after immobilization with Or35a integrated into the lipid bilayers of liposomes were conducted in the presence of four different redox probes. Potassium ferri/ferrocyanide [Fe(CN)₆]^3?/[Fe (CN)₆]^4? and hydroquinone (H₂Q) redox probes revealed variable and irreversible signals at the time scale of our measurements, with atomic force microscopy (AFM) images and x‐ray photoelectron spectroscopy (XPS) results suggesting gold surface etching due to the presence of CN^? ions in case of [Fe(CN)₆]^3?/[Fe (CN)₆]^4?. Although the hexaammineruthenium complex showed stable electrochemical behaviour at all stages of biosensor development, changes in CV and EIS readings after each surface modifications were insignificant. PBS buffer as a non‐Faradaic medium, was found to provide reliable systems for electrochemical probing of modified gold electrodes with Or35a/liposomes in aqueous media. Using this system, we have shown that this novel biosensor can detect its known odorant E2‐hexenal selectively compared to methyl salicylate down to femtomolar concentration.     

Constant flux relation for aggregation models with desorption and fragmentation

We study mass fluxes in aggregation models where mass transfer to large scales by aggregation occurs alongside desorption or fragmentation. Two models are considered: (1) a system of diffusing, aggregating particles with influx and outflux of particles (in-out model); and (2) a system of diffusing aggregating particles with fragmentation (chipping model). Both these models can exist in phases where probability distributions are power laws. In these power law phases, we argue that the two point correlation function should have a certain homogeneity exponent. These arguments are based on the exact constant flux scaling valid for simple aggregation with input. Predictions are compared with Monte Carlo simulations.     

Fabrication of gold sphere to cuboid nanoarrays using PDMS templates

A novel polymer based templated approach to creating highly ordered gold arrays with either positive or negative nano-scale features of controlled shape from truncated spheres to cuboids is presented.     

Synthesis and characterization of cyclotriphosphazenes containing silicon as single solid-state precursors for the formation of silicon/phosphorus nanostructured materials

The synthesis and characterization of new organosilicon derivatives of N(3)P(3)Cl(6), N(3)P(3)[NH(CH(2))(3)Si(OEt)(3)](6) (1), N(3)P(3)[NH(CH(2))(3)Si(OEt)(3)](3)[NCH(3)(CH(2))(3)CN](3) (2), and N(3)P(3)[NH(CH(2))(3)Si(OEt)(3)](3)[HOC(6)H(4)(CH(2))CN](3) (3) are reported. Pyrolysis of 1, 2, and 3 in air and at several temperatures results in nanostructured materials whose composition and morphology depend on the temperature of pyrolysis and the substituents of the phosphazenes ring. The products stem from the reaction of SiO(2) with P(2)O(5), leading to either crystalline Si(5)(PO(4))(6)O, SiP(2)O(7) or an amorphous phase as the glass Si(5)(PO(4))(6)O/3SiO(2).2P(2)O(5), depending on the temperature and nature of the trimer precursors. From 1 at 800 degrees C, core-shell microspheres of SiO(2) coated with Si(5)(PO(4))(6)O are obtained, while in other cases, mesoporous or dense structures are observed. Atomic force microscopy examination after deposition of the materials on monocrystalline silicon wafers evidences morphology strongly dependent on the precursors. Isolated islands of size approximately 9 nm are observed from 1, whereas dense nanostructures with a mean height of 13 nm are formed from 3. Brunauer-Emmett-Teller measurements show mesoporous materials with low surface areas. The proposed growth mechanism involves the formation of cross-linking structures and of vacancies by carbonization of the organic matter, where the silicon compounds nucleate. Thus, for the first time, unique silicon nanostructured materials are obtained from cyclic phosphazenes containing silicon.     

Layered graphitic carbon host formation during liquid-free solid state growth of metal pyrophosphates

We report a successful ligand- and liquid-free solid state route to form metal pyrophosphates within a layered graphitic carbon matrix through a single step approach involving pyrolysis of previously synthesized organometallic derivatives of a cyclotriphosphazene. In this case, we show how single crystal Mn(2)P(2)O(7) can be formed on either the micro- or the nanoscale in the complete absence of solvents or solutions by an efficient combustion process using rationally designed macromolecular trimer precursors, and present evidence and a mechanism for layered graphite host formation. Using in situ Raman spectroscopy, infrared spectroscopy, X-ray diffraction, high resolution electron microscopy, thermogravimetric and differential scanning calorimetric analysis, and near-edge X-ray absorption fine structure examination, we monitor the formation process of a layered, graphitic carbon in the matrix. The identification of thermally and electrically conductive graphitic carbon host formation is important for the further development of this general ligand-free synthetic approach for inorganic nanocrystal growth in the solid state, and can be extended to form a range of transition metals pyrophosphates. For important energy storage applications, the method gives the ability to form oxide and (pyro)phosphates within a conductive, intercalation possible, graphitic carbon as host-guest composites directly on substrates for high rate Li-ion battery and emerging alternative positive electrode materials.