Influence of rubbing conditions of polyimide alignment layer on optical anisotropy of immobilized liquid crystal film

The relationship between the molecular orientation of a rubbed polyimide film (alignment layer) and that of mesogens in a photopolymerized liquid crystal (LC) coated on the film has been investigated using optical measurements. LC monomers were deposited on the alignment layer and were aligned in one direction. The LC monomers were subsequently photocured. Alignment layers under various rubbing conditions were prepared. It was found that the inclination angle of the refractive index ellipsoid and the optical retardation of photopolymerized LC films are strongly related to the optical anisotropy of the rubbed polyimide film. The photopolymerized LC film exhibited high optical anisotropy when alignment layers with an inclination angle of the refractive index ellipsoid smaller than 6° were used.     

Vocal fold vibration of the canine larynx: Observation from an infraglottic view

The authors studied the vibratory action of the canine vocal fold from the tracheal side utilizing high-speed cinematography. Five excised canine larynges were used, and the lower surface of the vocal fold of three of them were marked with India ink as a tracer of a specific point on the vocal fold. A mucosal prominence, called the mucosal upheaval, appeared between the anterior commissure and the vocal process. Vibration was not seen below the mucosal upheaval. The mucosal wave started to move medially from just above the mucosal upheaval. The mucosal wave then became the free edge (lower lip) and collided with that of the other side at the midline. After collision, the lower lip moved upward to become the upper lip. At the same time, a part of the lower lip reflected laterally. The mucosal wave of the next cycle started from just above the mucosal upheaval during an opening phase. The mucosal upheaval vibrated with a low amplitude and with an earlier phase than the other portion of the vocal fold. The increase in tension of the vocal fold did not change the basic vibratory pattern of the mucosal upheaval, the mucosal wave, or the free edge. However, analysis of the mark before and after the increase in tension revealed that the mucosal upheaval occurred more medially or above when the vocal fold tension increased.     

Lipophilic arsenic compound(s) in the liver of a tiger shark (Galeocerdo cuvier)

Homogenized aliquots (100 g) of the liver (8.4 kg, 5 m?g As g^?1) of a tiger shark (Galeocerdo cuvier) were extracted with chloroform/methanol, and the extracts purified by countercurrent extraction (hexane/87% ethanol), silica gel column chromatography (chloroform/methanol mixtures as mobile phases), and silica gel thin-layer chromatography (chloroform/methanol/acetic acid). The purified samples (24 mg arsenic g^?1) gave no ³¹P NMR signal, but gave ¹H and ¹³C NMR signals with similarities to those of dipalmitoylphosphatidic acid and salad on and also signals indicative of the presence of methylated arsenic compounds. The sample could contain a diacyl glyceride with a methylated arsenic group.     

Photochemical generation of C4'-oxidized abasic site containing oligodeoxynucleotide and its efficient amine modification

[Structure: see text] We synthesized oligodeoxynucleotide (ODN, 3), which contains 4'-o-nitrobenzyloxythymidine (4) as a caged precursor of C4'-oxidized abasic site (1). Photoirradiation of 3 at 365 nm followed by amine treatment under neutral conditions afforded the lactam (2) efficiently. Duplexed ODN 3 was converted to 1 faster and more efficiently than single stranded 3, whereas amine treatment of 1 formed from single stranded 3 resulted in slightly faster lactam formation than with the duplex.     

Concise asymmetric total synthesis of lycopodine and flabelliformine via cascade cyclization reaction

The shortest asymmetric total synthesis of lycopodine (3) and the first asymmetric total synthesis of flabelliformine (4) were accomplished by a strategy that features a cascade cyclization of linear substrate (5) to construct tetracyclic structure (6).     

Synthesis and hybridization properties of l-oligodeoxynucleotide analogues fixed in a low anti glycosyl conformation

We have synthesized l-type enantiomers (cU and cA) of nucleoside analogues, whose glycosyl bonds are fixed in a low anti conformation (ap glycosyl conformation, [small chi][approximate] 180[degree]), and incorporated them into oligonucleotides to evaluate the hybridization ability with natural DNA and RNA sequences. Although the incorporation of the modified nucleosides into oligonucleotides decreased the hybridization ability with unmodified complementary DNA sequences, the fully-substituted 12mers (cU(12) and cA(12)) still retained the hybridization ability with the complementary unmodified DNA 12mers, regardless of their unnatural l-chirality. In contrast, cU(12) and cA(12) showed different hybridization behavior with complementary unmodified RNA 12mers. cU(12) forms a more stable duplex with rA(12) than the corresponding natural 12mer (dT(12)), whereas cA(12) cannot hybridize with rU(12). Based on the model structure of cU(12)-rA(12), we discuss these experimental results.     

Probabilistic Methods for Decomposition Dimension of Graphs

In a graph G, the distance from an edge e to a set FE(G) is the vertex distance from e to F in the line graph L(G). For a decomposition of E(G) into k sets, the distance vector of e is the k-tuple of distances from e to these sets. The decomposition dimension dec(G) of G is the smallest k such that G has a decomposition into k sets so that the distance vectors of the edges are distinct. For the complete graph K _n and the k-dimensional hypercube Q _k , we prove that (2–o(1))lgndec(K _n )(3.2+o(1))lgn and k/lgk dec(Q _k ) (3.17+o(1))k/lgk. The upper bounds use probabilistic methods directly or indirectly. We also prove that random graphs with edge probability p such that p n ^1– for some positive constant have decomposition dimension (lnn) with high probability. Acknowledgments.The authors thank Noga Alon for clarifying and strengthening the results in Sections 3 and 4. Thanks also go to a referee for repeated careful readings and suggestions.AMS classifications: 05C12, 05C35, 05D05, 05D40     

Crystal structures of deprotonated nucleobases from an expanded DNA alphabet

Reported here is the crystal structure of a heterocycle that implements a donor–donor–acceptor hydrogen‐bonding pattern, as found in the Z component [6‐amino‐5‐nitropyridin‐2(1H)‐one] of an artificially expanded genetic information system (AEGIS). AEGIS is a new form of DNA from synthetic biology that has six replicable nucleotides, rather than the four found in natural DNA. Remarkably, Z crystallizes from water as a 1:1 complex of its neutral and deprotonated forms, and forms a `skinny' pyrimidine–pyrimidine pair in this structure. The pair resembles the known intercalated cytosine pair. The formation of the same pair in two different salts, namely poly[[aqua(μ₆‐2‐amino‐6‐oxo‐3‐nitro‐1,6‐dihydropyridin‐1‐ido)sodium]–6‐amino‐5‐nitropyridin‐2(1H)‐one–water (1/1/1)], denoted Z‐Sod, {[Na(C₅H₄N₃O₃)(H₂O)]·C₅H₅N₃O₃·H₂O}_n, and ammonium 2‐amino‐6‐oxo‐3‐nitro‐1,6‐dihydropyridin‐1‐ide–6‐amino‐5‐nitropyridin‐2(1H)‐one–water (1/1/1), denoted Z‐Am, NH₄⁺·C₅H₄N₃O₃⁻·C₅H₅N₃O₃·H₂O, under two different crystallization conditions suggests that the pair is especially stable. Implications of this structure for the use of this heterocycle in artificial DNA are discussed.     

Advancement of Hard X-ray Nano-focusing Ellipsoidal Mirror at SPring-8

Ellipsoidal mirror optics can produce a smaller, two-dimensional focus with diffraction-limited properties than is possible when using mirror optics in Kirkpatrick–Baez (K–B) geometry [1 P. Kirkpatrick and A.V. Baez, Journal of the Optical Society of America 38, 766–773 (1948).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]]. This is because ellipsoidal focusing mirrors can be designed such that they have a larger numerical aperture in the sagittal focusing direction as compared to that in the meridional focusing direction. Although ellipsoidal focusing mirrors have this crucial advantage over K–B optics, K–B optics are widely utilized as micro-/nano-focusing devices [2 H. Mimura, Nature Physics 6, 122–125 (2010).[Crossref], [Web of Science ®] , [Google Scholar]–8 H. Mimura, Nature Communications 5, 3539 (2014).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]] in synchrotron radiation facilities and X-ray free electron laser facilities [9 P. Emma, Nature Photonics 4, 641–647 (2010).[Crossref], [Web of Science ®] , [Google Scholar], 10 T. Ishikawa, Nature Photonics 6, 540–544 (2012).[Crossref], [Web of Science ®] , [Google Scholar]]. Figure 1 shows a schematic of focusing mirror optics; Figure 1(a) shows the ellipsoidal mirror and Figure 1(b) the K–B mirror arrangement. In K–B geometry, two mirrors with a one-dimensionally curved surface, such as an elliptical cylinder, are orthogonally arranged in tandem to reflect and focus light independently in a direction perpendicular to each other under grazing-incidence conditions. Ellipsoidal focusing mirrors, which can generate a two-dimensional focusing beam by a single reflection, have a highly sloped surface with a two-dimensional aspherical shape, when compared to elliptical-cylinder mirrors that are used for line-focusing in K–B geometry. In addition, surface shapes of nano-focusing mirrors must be fabricated with nanometer-level accuracy. Therefore, fabrication of ellipsoidal nano-focusing mirrors is extremely difficult. There are no reports on ellipsoidal nano-focusing mirrors in the hard X-ray region with superior performances to provide diffraction-limited beams.