ESR, zero-field splitting, and magnetic exchange of exchange-coupled copper(II)-copper(II) pairs in copper(II) tetraphenylporphyrin N-oxide

The crystal structures of the dimer form of copper(II) tetraphenylporphyrin N-oxide, [Cu(tpp-N-O)]2 (3-dimer), and zinc(II) tetraphenylporphyrin N-oxide, [Zn(tpp-N-O)]2 (4-dimer), were established. The geometry at the copper ion in 3-dimer is essentially square-pyramidal with one oxygen bridge [O(1A)] occupying the apical site, giving a much larger Cu-O bond distance compared to those at the basal plane. The respective Cu...Cu distance and Cu-O-Cu angle in the core of 3-dimer are 3.987(4) A and 148.1(3) degrees. The Zn(1) atom in 4-dimer has a distorted square-pyramidal [4 + 1] coordination geometry that gives a tau-value of 0.19. The respective Zn...Zn distance and Zn-O-Zn angle in the dimeric unit of 4-dimer are 4.025(3) A and 148.1(2) degrees. The 3-dimer displays axial X-band electron paramagnetic resonance spectral features (Es = 0) in the powder state at 4 K, giving g parallel = 2.51 (A(parallel,s) = (9.6 +/- 0.2) x 10-3 cm(-1)) and g(perpendicular) = 2.11 and in the same powder state at 293 K giving Ds = 0.0731 cm(-1) (as derived from DeltaMs = 1 lines) or 0.0743 cm(-1) (as derived from the DeltaMs = 2 lines). In addition, 3-dimer displays a DeltaMs = 2 transition at g = 4.17 indicating the presence of spin-exchange coupling. The anisotropic exchange interaction (Ds(ex)= 0.132 cm(-1)) gives the main contribution to Ds in 3-dimer. The theoretical fit of the susceptibility and effective magnetic moment data of 3-dimer in the temperature range of 5-300 K gives 2J = 68 cm(-1), g = 2.01, p = 0.06, and a temperature-independent paramagnetism of 10(-6) cm3 mol(-1). This magnetic susceptibility data indicates that the copper(II) ions in 3-dimer are coupled in a ferromagnetic manner with the ground-spin triplet stabilized by 68 cm(-1) with regard to the singlet.     

Dynamics of supercooled water in various mesopore sizes

Double-quantum-filtered NMR and T(1) inversion-recovery spectroscopy were employed to exploit the temperature-dependent dynamics of D(2)O confined in MCM-41. Samples with three pore sizes of 1.58, 2.03, and 2.34 nm and two D(2)O contents were investigated. The reorientation correlation times of confined D(2)O in variously sized pores exhibit different temperature dependencies. The results reveal that the D(2)O molecules at fast motion site remain mobile below approximately 225 K and a liquid-liquid phase transition occurs around this temperature for all samples studied. This temperature is thought to be unreachable for supercooled D(2)O. Particularly, in 20 wt % D(2)O loaded samples with pore diameters of 1.58 and 2.03 nm, the reorientational correlation times of D(2)O at fast motion site exhibit Arrhenius behavior between 225 and 290 K, while other samples show power law dependency. Thus, a liquid phase of the fragile type in bigger pores changes to the strong type in samples with smaller pores.     

Alternative formulation and dynamic process for the efficient Banzhaf–Owen index

We adopt excess functions to propose alternative formulation and dynamic process for the efficient Banzhaf–Owen index.     

Deboronation-induced ratiometric emission sensing of fluoride by 1,3,5-tris-(o-carboranyl-methyl)benzene

1,3,5-Tris-(o-carboranyl-methyl)benzene (closo-1) and its nido-form (nido-1) were synthesized and fully characterized. The solid-state molecular structure of closo-1 was determined by single-crystal X-ray diffraction analysis. Compound closo-1 exhibited an intense single emission in various organic solvents that was red-shifted with increasing solvent polarity. The positive solvatochromic effect and theoretical calculation results at the first excited (S₁) optimized structure of closo-1 strongly suggest that this emissive band can be assigned to an intramolecular charge transfer. Meanwhile, nido-1 showed a pronounced red-shift of the emissive band compared to that of closo-1 and aroused low-energy emission. The specific emissive features of nido-1 were attributed to the elevation of its HOMO level, estimated by cyclic voltammetry. The photophysical changes by conversion from closo-1 to nido-1 allowed the emissive color-tunable sensing of fluoride. Thus, the tris-o-carboranyl compound showed great potential as a chemodosimeter for fluoride anion sensing, detectable by the naked-eye.     

Effect of filament biasing on nanocrystalline-Si films deposited by hot wire chemical vapor deposition

Nanocrystalline silicon (nc-Si) films were deposited by hot wire chemical vapor deposition with applying positive or negative filament biases. These films were characterized by Raman spectroscopy, field emission scanning electron microscopy and X-ray photoelectron spectroscopy. Plasmon loss of the Si(2p) band region was shifted to higher energy due to dielectric changes with applied filament biases from negative to positive voltage. A semi-quantitative study of the valence band structure was employed to analyze the bias effect of the valance band in nc-Si networks. Nc-Si with a positive filament bias shows better microstructural properties than those with a negative bias and without biasing nc-Si films.     

Modeling and large sample estimation for multi-casting autoregression

Multi-casting autoregression (MCAR, for short) is suggested as a natural extension of the bifurcating autoregressive (BAR) model (cf. [Cowan, R., Staudte, R.G., 1986. The bifurcating autoregression model in cell lineage studies. Biometrics 42, 769–783]) in order to analyze multi-splitting tree-structured data. Pathwise stationarity of the MCAR model is discussed. Least squares estimation for the autoregressive parameter is considered and relevant limiting distribution is derived, in particular, for the pathwise explosive case. These results can be regarded as generalizations of those for standard stationary and explosive AR(1) time series. A simulation study is conducted to illustrate our results.     

Photochemical Activities of N‐Nitroso Carboxamides and Sulfoximides and Their Application to DNA Cleavage

N‐Nitroso compounds containing benzene, fluorene or fluorenone rings were synthesized. Photolysis of these compounds with 312‐nm UV light provided the NO ^. species, the presence of which was corroborated by use of an EPR method and of 2‐phenyl‐4,4,5,5‐tetramethylimidazolin‐1‐oxyl 3‐oxide (PTIO) as a trapping agent. During irradiation of N‐methyl‐N‐nitroso‐9‐fluorenone carboxamide ( 14 c ) in the absence of PTIO, it underwent decomposition followed by recombination to give the heterocyclic nitric oxide radical 15 . Incorporation of intercalating moieties endowed the N‐nitroso compounds with DNA‐cleaving ability through single‐strand scission upon UV irradiation in a phosphate buffer (pH 5.0–8.0) under aerobic conditions.     

A novel architecture of poly(tetrafluoroethylene)-framed TiO2 electrodes for dye-sensitized solar cells

A novel architecture of polytetrafluoroethylene (PTFE)-framed TiO₂ electrodes is developed for dye-sensitized solar cells. The PTFE-framed TiO₂ electrodes with various thicknesses have been successfully fabricated, ranging from 20 to 160 μm. The optimal energy conversion efficiency of 9.04% is achieved with a film thickness of 60 μm. The PTFE-framed structure not only provides tunable film thickness but a reliable and cost-effective way for the mass production of photo-electrodes.     

Size effect in plastically deformed passivated thin films

The flow theory of mechanism-based strain gradient plasticity theory (MSG) developed by Qiu et al. (2003) is extended for incompressible material. The MSG flow theory is used to predict the increase of plastic work hardening for plane strain tension of surface-passivated Cu thin film. The theoretical predictions agree well with experiments for suitably chosen material parameters. Contributed by HWANG Keh-Chih     

Influence of reactive oxygen species on the sterilization of microbes

The influence of reactive oxygen species on living cells, including various microbes, is discussed. A sterilization experiment with bacterial endospores reveals that an argon–oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby indicating that oxygen radicals are the key element of sterilization. Ozone in acidic water also kills endospores of B. atrophaeus very effectively, demonstrating the capability of cleaning a large surface area contaminated by toxic biological agents. The viable microbe numbers after the contact with acidic ozone water directly correlate with increase in the ozone decay time in water after lowering the pH value of water from pH = 7 to 4 indicating that acidic ozone water is an effective means of sterilizing microbes. However, advanced cells such as fertilized eggs were not greatly influenced by the acidic ozone water. Also, both human and canine cells after treatment with the acidic ozone water prospered without showing signs of stress due to ozone in acidic water. This study suggests that antioxidant enzymes such as superoxide dismutase can be developed in the advanced cells to protect themselves from attacks by reactive oxygen species. Meanwhile, the advanced cells utilize oxygen by certain enzymes, proliferating life on earth.