Uniaxial alignment of nematic liquid crystals filling vacant spaces in surface-treated nanofibre nonwoven

ABSTRACT

Nematic liquid crystals (NLCs) absorbed in a nonwoven of surface-treated silica nanofibres (SiO₂-NFs) orient the director along the nonwoven thickness direction if the NLCs prefer homeotropic anchoring onto the fibre surface. The nonwoven has vacant spaces with the dimensions of 0.3 and 0.6 μm in the thickness and cross directions, respectively, bordered with SiO₂-NFs with 93 nm in diameter. The SiO₂-NF surface was treated with a silane-coupling agent to induce the homeotropic anchoring of NLC mesogens onto the surface. The nematic director is arranged radially from the fibres although it is more severely constrained by the proximity between fibre surfaces along the thickness direction. Consequently, the NLCs can align along the nonwoven thickness direction involving ?1/2 wedge disclinations on both sides of the fibres.     

Crystal structure of the pyrochlore oxide superconductor KOs2O6

We report the single-crystal X-ray analysis of the structure of the pyrochlore oxide superconductor KOs₂O₆. The structure was identified as the β-pyrochlore structure with space group and lattice constant at : the K atom is located at the 8b site, not at the 16d site as in conventional pyrochlore oxides. We found an anomalously large atomic displacement parameter at for the K cation, which suggests that the K cation weakly bound to an oversized Os₁₂O₁₈ cage exhibits intensive rattling, as recently observed for clathrate compounds. The rattling of A cations is a common feature in the series of β-pyrochlore oxide superconductors AOs₂O₆ (A=Cs, Rb and K), and is greatest for the smallest K cation.     

Kinetic determination of cysteine on flow injection system by utilizing catalytic complexation reaction of Cu(II) with 5,10,15,20-tetrakis (4-N-trimethylammino-phenyl) porphyrin

A kinetic method for the determination of cysteine on flow injection system is described. Cysteine was found as a catalyst for the complexation reaction of Cu(II) with an ultra sensitive colorimetric reagent of 5,10,15,20-tetrakis (4-N-trimethylammino-phenyl) porphyrin (TTMAPP) (varepsilon=4.8x10(5)cm(-1)M(-1) at 433nm), which was used as the indicator reaction in this paper. Soret band of either the porphyrin or the produced complex (varepsilon=4.6x10(5)cm(-1)M(-1) at 411nm) can be used for detection. The continuous flow injection system greatly enhanced the analytic precision and efficiency of the kinetic method, giving a relative standard deviation of 0.73% for a 0.1mugml(-1) cysteine with 10 injections at a throughput of 30h(-1). The detection limits (3S/N) in this case was 15ngml(-1) and the working dynamic range was over 25ngml(-1) to 1mugml(-1). Sugars, organic acids and amino acids that are possible in coexistence with cysteine could be tolerated at high concentrations. This method was critically compared with the Ellman's reagent in the determinations of cysteine contents of three pharmaceutical injections for hepatic diseases and one permanent wave agent and showed better applicability in the respect of matrix interferences.     

Absorption Spectra of Planarian Visual Pigments and Two States of the Metarhodopsin Intermediates

Abstract— Absorption spectra measurements of isolated planarian ocelli by a microspectrophotometer (MSP) and intra-ocellar recordings of the early receptor potential (ERP) were carried out in order to characterize in situ planarian rhodopsin (pRh) and its photoproducts. The MSP spectra of the isolated ocelli revealed Λ_max at about 500 nm. The ERP evoked by a test stimulus was a positive monophasic waveform in the dark but became negative during exposure to violet light. During subsequent darkness, the ERP rapidly reverted to a positive waveform but with a smaller amplitude than before exposure. The ERP amplitude recovered to its initial level upon exposure to red light. The ERP experiments suggest that pRh produces two metarhodopsin intermediates, with Λ_max longer than that of pRh: the metastate responsible for the negative ERP converts to another metastate that results in a smaller ERP in the dark-adapted ocellus.     

Pyrimidine dimer formation and oxidative damage in M13 bacteriophage inactivation by ultraviolet C irradiation

The mechanism by which UV-C irradiation inactivates M13 bacteriophage was studied by analyzing the M13 genome using agarose gel electrophoresis and South-Western blotting for pyrimidine dimers. The involvement of singlet oxygen (1O2) was also investigated using azide and deuterium oxide and under deoxygenated conditions. With a decrease in M13 infectivity on irradiation, single-stranded circular genomic DNA (sc-DNA) was converted to Form I and Form II, which had an electrophoretic mobility between that of sc-DNA and linear-form DNA. However, the amount of sc-DNA remaining was not correlated with the survival of M13. The formation of cyclobutane pyrimidine dimers (CPD) and pyrimidine (6-4) pyrimidone photoproducts ((6-4)PP) increased as a function of irradiation dose. The decrease in M13 infectivity was highly correlated with the increase in CPD and (6-4)PP, whereas no change was seen in M13 coat protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 8-Oxo-7,8-dihydro-2'-deoxyguanosine did not form in the M13 genome after UV-C irradiation. Inactivation of M13 was neither enhanced by deuterium oxide nor inhibited by azide. Deoxygenation of the M13 suspension did not affect the inactivation, indicating that 1O2 did not participate in the inactivation of M13 by UV-C irradiation under these conditions. These results indicated that UV-C irradiation induced not only CPD and (6-4)PP formation but also additional tertiary structural change in DNA inside the M13 virions, resulting in primary damage and a loss of infectivity. The indirect effect of UV-C irradiation such as 1O2 production followed by oxidative damage to nucleic acids and proteins might have contributed less, if at all, to the inactivation of M13 than the direct effect of UV-C.     

Redox reaction of μ−O in water determined by the chemical shift

The chemical shift of ^–O in water, ice and in aqueous hydrogen peroxide (H₂O₂) was examined using ^–O resonance. Two distinct signals are obtained in water and ice. Using ⁺ resonance signal as a standard, the observed shiftsg are –7.0×10^–4 (signal A) and –12.1×10^–4 (signal B) respectively. The intensity of the two fractions are almost equivalent in water; however, in ice, the intensity of signal B decreases with increase of signal A. After the addition of hydrogen peroxide to the water signal B disappears, A increases, and the total amplitude is increased.     

Designed ferromagnetic, ferroelectric Bi(2)NiMnO(6)

A newly designed ferromagnetic, ferroelectric compound, Bi(2)NiMnO(6), was prepared by high-pressure synthesis at 6 GPa. The crystal structure, as determined by synchrotron X-ray powder diffraction, is a heavily distorted double perovskite with Ni(2+) and Mn(4+) ions ordered in a rock-salt configuration. The presence of 6s(2) lone pairs of Bi(3+) ions and the covalent Bi-O bonds give ferroelectric properties with T(CE) of 485 K, while -Ni(2+)-O-Mn(4+)-O-Ni(2+)- magnetic paths lead to a ferromagnetism with T(CM) of 140 K. This simple material design to distribute two magnetic elements with and without e(g) electrons on B sites of Bi- and Pb-based perovkites can be applied to other Bi(2)M(2+)M'(4+)O(6) and Pb(2)M(3+)M'(5+)O(6) systems to search for newer ferromagnetic ferroelectrics.