Thermal and optical properties of newly synthesized dicholesteryl esters with a phenylene oxide link in the normal and solidified cholesteric phases

A series of liquid crystalline compounds with a central phenylene oxide group to which two cholesteryl groups are attached via two alkanoate spacers has been synthesized and investigated. All the compounds except the one with ethanoate spacers showed a cholesteric phase as a single mesophase. The phase transition temperatures, the corresponding enthalpy changes and the wavelengths of selective reflection associated with the cholesteric phases showed a strong odd-even effect as a function of the spacer length. By rapid cooling of the compounds from the cholesteric phase to 0°C, solid films maintaining a cholesteric molecular order were obtained. At room temperature, the solid film showed stable cholesteric colours controlled by changing the temperature at which the rapid cooling was begun. Heating the cholesteric solid film of the compound with hexanoate spacers gave two forms of crystals above 80°C, whose ratio changed depending on the colour of the starting solid films. This result suggests the existence of two conformational isomers in the liquid crystalline state. Since it is possible repeatedly to fix stable red, green and blue colours by thermal treatment of this compound, we may apply it to a rewritable full colour recording in the thermal mode.     

Additivity rule holds in the hydrogen transfer reactivity of unsaturated fatty acids with a peroxyl radical: mechanistic insight into lipoxygenase

A simple additivity rule holds in the hydrogen transfer reactivity of unsaturated fatty acids with cumylperoxyl radical, which is expressed by the additive contributions of the reactivity of active hydrogens from the 1,4-pentadiene subunit and those of the allylic subunit; the kinetic isotope effect on the hydrogen transfer reactions (KIE = 6.1) is significantly smaller than that observed for lipoxygenase (KIE = 81).     

Two equivalent measures on weighted hypergraphs

Let H=(N,E,w) be a hypergraph with a node set N={0,1,…,n-1}, a hyperedge set E⊆2^N, and real edge-weights w(e) for e∈E. Given a convex n-gon P in the plane with vertices x₀,x₁,…,x_n-1 which are arranged in this order clockwisely, let each node i∈N correspond to the vertex x_i and define the area A_P(H) of H on P by the sum of the weighted areas of convex hulls for all hyperedges in H. For 0?i<j<k?n-1, a convex three-cut C(i,j,k) of N is {{i,…,j-1}, {j,…,k-1}, {k,…,n-1,0,…,i-1}} and its size c_H(i,j,k) in H is defined as the sum of weights of edges e∈E such that e contains at least one node from each of {i,…,j-1}, {j,…,k-1} and {k,…,n-1,0,…,i-1}. We show that the following two conditions are equivalent:

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A_P(H)?A_P(H^′) for all convex n-gons P.

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c_H(i,j,k)?c_H^′(i,j,k) for all convex three-cuts C(i,j,k).

From this property, a polynomial time algorithm for determining whether or not given weighted hypergraphs H and H^′ satisfy “A_P(H)?A_P(H^′) for all convex n-gons P” is immediately obtained.     

Atomic layer epitaxy of AlP and (AlP)n(GaP)n superlattice using ethyldimethylamine alane as a new aluminum source

Atomic layer epitaxy (ALE) of AlP was realized using ethyldimethylamine alane (EDMAAl) as a new Al source. Self-limiting growth of AlP took place at one and two monolayers per ALE cycle. Secondary ion mass spectroscopy revealed that the amounts of incorporated impurities (carbon, hydrogen and oxygen) in ALE-grown AlP layers was greatly suppressed by using the new Al source, to nearly the same levels as in high-quality MOVPE-grown layers. We also achieved the successful ALE growth of (AlP)_n(GaP)_n short-period superlattices (SLs), taking advantage of the overlapping temperature windows of ALE-GaP and ALE-AlP. X-ray diffraction measurements showed reasonably good interface abruptness of SLs as low as 3. The PL emission peak from SLs involving Al-containing layers was observed in ALE growth for the first time.     

Diffraction-Based Spatial Light Modulation: Transverse Linear Electrooptic Effect in Polymers

We propose a new type of spatial light modulator using nonlinear organic polymer film as a phase modulation element. Using polymer poly-Disperse Red-19 Toluendiiso-cyanate, a more than 150:1 contrast ratio has been realized for electrical addressing in transverse geometry.     

Plasmas as an exotic target for heavy ion physics and spectroscopy

Following a short introduction of heavy ion collision physics relevant to fusion plasma researches and related to fusion technology, some exotic features of plasmas as a target for heavy ion collisions and spectroscopy have been discussed.     

Investigation of organelle‐specific intracellular water structures with Raman microspectroscopy

The study of intracellular water in living cells is a challenge of fundamental importance. While the critical roles of water in maintaining and propagating life have been widely recognized and accepted, our understanding of water/biomolecule interactions is surprisingly limited. Using Raman microspectroscopic imaging of a living yeast cell followed by a multivariate analysis in form of the nonnegative matrix factorization method, we successfully resolve organelle‐specific water structures. The intensities and the band profiles of the segregated water OH stretch spectra yield important and otherwise unobtainable information on the extensive effect of the water/biomolecule interactions in a given organelle on the hydrogen‐bonding network of water molecules. Copyright © 2012 John Wiley & Sons, Ltd.