Photocatalysis of Chloroform Decomposition by Tetrachlorocuprate (II) on Dowex 2‐X8

Heterogenized on a polystyrene anion exchange resin and in the presence of oxygen, catalyzes the photodecomposition of chloroform at wavelengths above 345 nm with greater efficiency than an equivalent amount in homogeneous solution. The reaction is proposed to proceed in two stages, the first stage yielding CCl₄ and as products, the second consisting of a chain reaction resulting from the ‐catalyzed photodissociation of CCl₄, yielding phosgene with CCl₃ radicals as chain carriers. Photodecomposition is retarded by added Cl^?, CH₃CN, C₆H₁₂ or C₂H₅OH, which is ascribed to the displacement of CHCl₃ molecules from the vicinity of the copper by attraction to the polystyrene matrix or to the alkylammonium cation sites.     

Investigating the acoustics of a sample of open plan and enclosed Kindergarten classrooms in Australia

Open plan classrooms, where several class bases share the same space, have recently re-emerged in Australian primary schools. This study compared the acoustics of four different Kindergarten classrooms: an enclosed classroom with 25 students, a double classroom with 44 students, a linear fully open plan triple classroom with 91 students, and a semi-open plan K-6 classroom with 205 students. Ambient noise levels, intrusive noise levels, occupied background noise levels, and teacher’s speech levels were recorded during different activities. Room impulse responses using logarithmic sweeps were also recorded for different teaching scenarios. From these recordings, signal-to-noise ratios, speech transmission index scores, and reverberation times were calculated. The results revealed much higher intrusive noise levels in the two largest open plan classrooms, resulting in signal-to-noise ratios and speech transmission index scores to be well below those recommended in classrooms with students of this age. Additionally, occupied background noise levels in all classrooms were well above recommended levels. These results suggest noise in classrooms needs to be better controlled, and open plan classrooms are unlikely to be appropriate learning environments for young children due to their high intrusive noise levels. The impact of noise on children’s learning and teacher’s vocal health are discussed.     

An indium tin oxide electrode modified with gold nanorods for use in potential-controlled surface plasmon resonance studies

The modification of electrodes with gold nanoparticles results in an increased electrode surface area, enhanced mass transport, and improved catalytic properties. We have extended this approach to indium tin oxide (ITO) electrodes to obtain optically transparent gold nanorod-modified electrodes which display enhanced electrochemical capabilities and have the additional advantage of showing a tunable surface plasmon resonance. The procedures for attaining high surface coverage (15 gold nanorods per square µm) of such electrodes were optimized, and the potential-dependent surface plasmon resonance was studied under controlled electrical potential. In an exemplary sensor application, we demonstrate the detection of mercury via potential-dependent formation of an Au-Hg amalgam.

Equilibrium Anionic Polymerization of p-lsopropyl-α-methylstyrene in Tetrahydrofuran

The equilibrium anionic polymerization of p-isopropyl-α-methylstyrene in tetrahydrofuran with potassium and sodium-naphthalene complex as initiators has been investigated in the temperature range of -20 to +20° C by use of high-vacuum techniques. The comparison of these results with those obtained previously for the equilibrium polymerization of α-methyl-styrene revealed that, because of the p- substituted bulkier isopropyl group in the monomer, the values of δG_c, the free-energy change upon the polymerization of 1 mole of liquid monomer to 1 base-mole of liquid amorphous polymer of infinite chain length, are slightly higher in the present studies. The values of ΔH_c and ΔS ^ccomputed from the plots of ΔG_c /RT versus 1/T yielded values which are lower than that for the α-methylstyrene-THF system. The effect of p-substitution is also observed in the higher values of the monomer equilibrium concentration [M] and lower values of β[β = x_ms-x_sp (V_m/V_s)].

where x_ms and x are monomer-solvent and solvent-polymer interaction parameters, respectively, and V_m /V_s is molar volume ratio of monomer to solvent. The values of x_ms for the p-isopropyl-α-methylstyrene-THF system increase regularly with increasing temperature, whereas in α-methylstyrene-THF system the increase in x^ms was not that marked     

Porous chromatographic materials as substrates for preparing synthetic nuclear explosion debris particles

Several porous chromatographic materials were investigated as synthetic substrates for preparing surrogate nuclear explosion debris particles. Eighteen metals, including some of forensic interest, were loaded onto materials by immersing them in metal solutions (556 mg/L of each metal) to fill the pores, applying gentle heat (110 °C) to drive off water, and then treating them at high temperatures (up to 800 °C) in air to form less soluble metal species. High-boiling-point metals were uniformly loaded on spherical controlled-pore glass to emulate early fallout, whereas low-boiling-point metals were loaded on core–shell silica to represent coated particles formed later in the nuclear fallout-formation process. Analytical studies characterized material balance and the formation of recalcitrant species. Metal loading was 1.5–3 times higher than expected from the pore volume alone, a result attributed to surface coating. Most metals were passively loaded; that is, solutions filled the pores without active metal discrimination. However, niobium and tin concentrations were lower in solutions after pore filling, and were found in elevated concentrations in the final products, indicating selective loading. High-temperature treatments caused reduced solubility of several metals, and the loss of some volatile species (rhenium and tellurium). Sample preparation reproducibility was high (the inter- and intra-batch relative standard deviations were 7.8 and 0.84 %, respectively) indicating suitability for use as a working standard for analytical methods development. We anticipate future standardized radionuclide-loaded materials will find use in radioanalytical methods development and/or serve as a starting material for the synthesis of more complex nuclear explosion debris forms (e.g., Trinitite).     

Interpretation of laser desorption mass spectra of unexpected inorganic species found in a cosmetic sample of forensic interest: fingernail polish

Monitoring of cell cultures in microbioreactors is a crucial task in cell bioassays and toxicological tests. In this work a novel tool based on a miniaturized sensor array fabricated using low-temperature cofired ceramics (LTCC) technology is presented. The developed device is applied to the monitoring of cell-culture media change, detection of the growth of various species, and in toxicological studies performed with the use of cells. Noninvasive monitoring performed with the LTCC microelectrode array can be applied for future cell-engineering purposes. Figure Microelectrode array for monitoring of cell cultures     

Enthalpy of fusion of poly(3‐hexylthiophene) by differential scanning calorimetry

The enthalpy of fusion for a perfect, infinite poly(3‐hexylthiophene) (P3HT) crystal () must be known to evaluate the absolute crystallinity of P3HT. This value, however, is still ambiguous as different values have been reported using various experimental techniques. Here, we extrapolate the enthalpy of fusion for extended chain crystals of oligomeric P3HT to infinite molecular weight and obtain a value of 42.9 ± 2 J/g employing differential scanning calorimetry with a correction based on grazing incidence small angle X‐ray scattering data. Also, we define the onset of chain folding within P3HT crystallites at a chain length of 5 Kuhn segments. Knowledge of allows calculation of P3HT percent crystallinity in thin films for applications such as organic field effect transistors and solar cells. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1469–1475     

Electrical conductivity and defect chemistry of {\hbox{B}}{{\hbox{a}}_x}{\hbox{S}}{{\hbox{r}}_{{1} - x}}{\hbox{C}}{{\hbox{o}}_y}{\hbox{F}}{{\hbox{e}}_{{1} - y}}{{\hbox{O}}_{{3} - \delta }} perovskites

Bulk $ {\hbox{B}}{{\hbox{a}}_x}{\hbox{S}}{{\hbox{r}}_{{1} - x}}{\hbox{C}}{{\hbox{o}}_y}{\hbox{F}}{{\hbox{e}}_{{1} - y}}{{\hbox{O}}_{{3} - \delta }} $ compositions (BSCF) were synthesized by the solid-state reaction method. The electrical conductivity of ceramic bars was measured using a dc four-probe method as a function of temperature in air up to 970?°C. All compositions showed thermally activated p-type semi-conductivity up to ~450?°C and then a transition to metal-like conductivity. The small-polaron hopping p-type semi-conductivity depends on the oxygen nonstoichiometry, which increases with increasing temperature. Metal-like conductivity is attributed to the overlap of the transition metal d-electron orbitals with the oxygen p-orbitals. Strontium-rich compositions show higher conductivity. The Co/Fe ratio does not influence much the p-type semi-conduction. Iron-rich compositions revealed more metal-like conduction behavior. The degree of overlap between transition metal d-orbitals and oxygen p-orbitals depends on the Ba/Sr as well as on the Co/Fe ratios.     

Experiments with longitudinally polarized electrons in a storage ring using a siberian snake

We report on first measurements with polarized electrons stored in a medium-energy ring and with a polarized internal target. Polarized electrons were injected at 442 MeV (653 MeV), and a partial (full) Siberian snake was employed to preserve the polarization. Longitudinal polarization at the interaction point and polarization lifetime of the stored electrons were determined with laser backscattering. Spin observables were measured for electrodisintegration of polarized 3He, with simultaneous detection of scattered electrons, protons, neutrons, deuterons, and 3He nuclei, over a large phase space.