Reversible color changes in lamella hybrids of poly(diacetylenecarboxylates) incorporated in layered double hydroxide nanosheets

The present study is an investigation of a reversible thermal color change induced in lamella hybrids of poly(diacetylenecarboxylates) incorporated in layered double hydroxide (LDH) nanosheets. These poly-[m,n]/LDH hybrids prepared by the photo- or gamma-ray-induced polymerization of diacetylenecarboxylates, i.e., CH(3)(CH(2))(m)()(-)(1)CC-CC(CH(2))(n)()(-)(1)CO(2)(-) (mono-[m,n]), and intercalated in LDH lamella sheets, were observed to develop colors ranging from yellow to blue. The change in color was found to depend greatly on the alkyl carbon numbers of the mono-[m,n] (m,n = 10,11; 5,11; 10,5; 16,1) values. Moreover, the conformational alignment of the mono-[m,n] within the LDH was observed to be a crucial factor in color development, which was greatly affected by the intercalation degrees and extent of poly(ene-yne) linkage elongation of the polymers. For the poly-[m,n]/LDH hybrids investigated, a reversible color change was found to occur repeatedly and remarkably for the poly-[10,11]/LDH hybrid. This color change occurred at temperatures between ca. 20 and 80 degrees C back and forth from purple red to bright orange, in stark contrast to the irreversible color change for poly-[10,11] without LDH. Moreover, DSC and Raman spectroscopic studies of the LDH hybrids showed that the thermochromic temperature corresponded to the phase transition temperature of 80 degrees C. XRD analysis also indicated that the poly-[m,n]/LDH hybrid could retain its lamella structure during such thermochromic color changes, enabling conformational recovery in the polymer chains by a cooling down of the hybrids to temperatures lower than the transition temperature, while the nonhybrid poly-[10,11] powders exhibited an irreversible color change at 60 degrees C, above which the polymer powder turned amorphous.     

Novel extracellular polymeric substances produced by Cupriavidus necator IPT 027 grown on glucose and crude glycerol originated from biodiesel

The aim of this study was to evaluate the production and properties of novel extracellular polymeric substances (EPS) from glucose (EPS 1) and crude glycerol (CG) from castor beans oil (EPS 2). Cupriavidus necator IPT 027 cultivated with glucose and CG (35 °C, 150 rpm, 72 hr, pH 7, shaker) produced approximately 1.60 ± 0.01 and 2.83 ± 0.02 g l^?1 EPS, respectively, with high‐molecular weight (3.89 × 10⁵ and 1.89 × 10⁷ Da) and constituted of different functional groups such as uronic acid, monosaccharides (glucose, mannose, arabinose, and fucose) and primary amine group. The composition of the fermentable substrate influenced the melting temperature (221.11 and 230.18 °C), crystallinity (34.36% and 37.11%), degradation temperature (255.06 and 296.62 °C) and morphology. EPS showed pseudoplastic non‐Newtonian fluid behavior in the aqueous solutions, presenting potential applicability biotechnological and industrial mainly in food industry as emulsifiers and biosurfactants. This is the first study on the production and characterization of EPS obtained by C. necator IPT 027 in culture with glucose and CG. Copyright © 2016 John Wiley & Sons, Ltd.     

Distribution of phospholipid molecular species in autogenous access grafts for hemodialysis analyzed using imaging mass spectrometry

Arteriovenous fistulae (AVF) using vein grafts are frequently used for vascular access in hemodialysis. When superficial veins are used as autogenous access grafts for hemodialysis, atherosclerotic-like tissue degeneration often causes stenosis and obstruction. Although the differences between the pathology of degeneration in AVF and atherosclerosis (i.e., peripheral artery occlusive disease (PAD)) are known, their underlying molecular mechanisms are not. We determined the characteristic abnormal lipid metabolism of AVF. Oil red O staining clearly showed the accumulation of lipid molecules in AVF and PAD tissues. We found that the staining pattern was different between AVF and PAD tissues. The media and adventitia of AVF and the intima and media of PAD were intensely stained. Quantitative lipid analysis revealed that the amount of PL was significantly increased in AVF and PAD. Next, we performed matrix-assisted laser desorption/ionization imaging mass spectroscopy and determined the characteristic distribution of lysophosphatidylcholine (LPC) and phosphatidylcholine (PC) in AVF. The distribution patterns of LPC (1-acyl 16:0) and PC (diacyl 16:0/20:4) were consistent with the Oil red O staining images, suggesting that metabolisms related to LPC (1-acyl 16:0) and PC (diacyl 16:0/20:4) are altered in AVF.     

High-quality InAlN/GaN heterostructures grown by metal–organic vapor phase epitaxy

We fabricated high-quality InAlN/GaN heterostructures by metal–organic vapor phase epitaxy (MOVPE). X-ray diffraction measurements revealed that InAlN/GaN heterostructures grown under optimal conditions have flat surfaces and abrupt heterointerfaces. Electron mobility from 1200 to 2000 cm²/V s was obtained at room temperature. To our knowledge, this mobility is the highest ever reported for InAlN/GaN heterostructures. We also investigated the relationship between the Al composition and sheet electron density (N_s) for the first time. N_s increased from 1.0×10¹² to 2.7×10¹³ cm⁻² when the Al composition increased from 0.78 to 0.89.     

Asymmetric benzoin condensation promoted by chiral triazolium precatalyst bearing a pyridine moiety

Chiral triazolium salts bearing a pyridine ring were developed as N-heterocyclic carbene precursors. In the presence of the chiral triazolium salt and a base, the catalytic asymmetric benzoin condensation proceeded to afford the product in high level of chemical yield and enantioselectivity. A wide range of aromatic aldehydes were applicable to this reaction.     

Age-dependent plasticity in the superior temporal sulcus in deaf humans: a functional MRI study

Background  

Sign-language comprehension activates the auditory cortex in deaf subjects. It is not known whether this functional plasticity in the temporal cortex is age dependent. We conducted functional magnetic-resonance imaging in six deaf signers who lost their hearing before the age of 2 years, five deaf signers who were >5 years of age at the time of hearing loss and six signers with normal hearing. The task was sentence comprehension in Japanese sign language.     

Construction of the benzylic quaternary carbon center of zoanthenol by intramolecular Mizoroki-Heck reaction of enone

[reaction: see text]. Stereocontrolled synthesis of the ABC ring framework of zoanthenol has been achieved. Our studies show that a beta,beta-disubstituted enone can act as a good acceptor of arylpalladium intermediates in the formation of a congested benzylic quaternary carbon center through an intramoleculer Mizoroki-Heck reaction. The cis B/C ring system was stereoselectively converted to the trans-fused framework through a SmI2-promoted deoxygenation of the alpha-hydroxy ketone.     

Fe3O4-LiMo3Se3 nanoparticle clusters as superparamagnetic nanocompasses

A scaleable chemical approach to functional nanoscale analogues of the magnetic compasses in magnetotactic bacteria is described. LiMo(3)Se(3)-Fe(3)O(4) nanowire-nanoparticle composites were synthesized by a reaction of 3-iodopropionic acid treated LiMo(3)Se(3) nanowire bundles with oleic acid-stabilized Fe(3)O(4) nanoparticles of 2.8, 5.3, and 12.5 nm size in tetrahydrofuran. Transmission electron micrographs show that the composite consists of Fe(3)O(4) nanoparticles attached to the surfaces of the 4-6 nm thick nanowire bundles. UV/vis spectra reveal absorptions from the nanowire (506 nm) and magnetite components (280-450 nm), and IR spectra show characteristic bands for the propionic acid linkers and for the residual oleic acid ligands on the magnetite particles. In the presence of excess oleic acid, the nanocomposites undergo rapid disassembly, suggesting that Fe(3)O(4) nanoparticles are bonded to nanowires via carboxylate groups from the linkers. Ultrasonication of a dispersion of the composite in THF produces individual LiMo(3)Se(3)-Fe(3)O(4) clusters, which are 340 +/- 107 nm long and 20 +/- 5 nm thick, depending on the sonication time and Fe(3)O(4) nanoparticle size. Field cooled and zero-field cooled magnetization measurements reveal that the blocking temperature (T(B) = 100 K) of the clusters with 5.3 nm Fe(3)O(4) is increased as compared to the free nanoparticles (T(B) = 30 K). Directional dipolar interactions in the clusters lead to magnetic anisotropy, which makes it possible to align the clusters in a magnetic field (900 Oe).     

Study of Si(0 0 1)4 × 2-Ga structure by scanning tunneling microscopy and ab initio calculation

We have studied Si(0 0 1)-Ga surface structures formed at Ga coverages of slightly above 0.50 monolayer (ML) at 250 °C by scanning tunneling microscopy (STM). 4 × 2-, 5 × 2-, and 6 × 2-Ga structures were observed in a local area on the surface. The 4 × 2-Ga structure consists of three protrusions, as observed in filled- and empty-state STM images. The characters of these structures are clearly different from those of other Si(0 0 1)-Ga structures. We also performed an ab initio calculation of the energetics for several possible models for the 4 × 2-Ga structure, and clarified that the three-orthogonal-Ga-dimer model is the most stable. Also, the results of comparing the simulated STM images and observation images at various bias voltages indicate that this structural model is the most favorable.     

Laser-induced fluorescence and infrared spectroscopic studies on the specific solvation of tris(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)europium(III) in an ionic liquid

The extraction constant and the two-phase stability constant (K_D,Mβ₃) of tris(2-thenoyltrifluoroacetonato)europium(III) between 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C₄mim][Tf₂N]) as an ionic liquid and an aqueous phase were determined by considering the extraction equilibria including anionic tetrakis(2-thenoyltrifluoroacetonato)europate(III). Specific solute-solvent interactions between the neutral Eu(III) chelate and [C₄mim][Tf₂N] molecules were revealed from the relationships between the distribution constant of the enol form of 2-thenoyltrifluoroacetone (Htta) as a proton chelate and the distribution constant (K_D,M) of the neutral Eu(III) chelate because the [C₄mim][Tf₂N] system gave the high K_D,Mβ₃ value compared with those in conventional molecular solvents such as benzene and 1,2-dichloroethane. The coordination environment of Eu³⁺ in the neutral Eu(III) chelate in [C₄mim][Tf₂N] was investigated by time-resolved laser-induced fluorescence spectroscopy and infrared absorption spectroscopy. Both methods consistently indicated that not only the Eu(III) chelate extracted but also Eu(tta)₃(H₂O)₃ synthesized as a solid crystal were almost completely dehydrated in [C₄mim][Tf₂N] saturated with water. Consequently, the higher K_D,M or extractability of the neutral Eu(III) chelate in the [C₄mim][Tf₂N] system can be ascribed to the dehydration of the Eu(III) chelate, which is caused by the specific solvation with [C₄mim][Tf₂N] molecules.