A polarized laser backlight using a zero-zero-birefringence polymer for liquid crystal displays

We have demonstrated a polarized laser backlight for liquid crystal displays and have investigated its basic polarization properties. To maintain the state of polarization of light propagating through the light-guide plate (LGP) of the backlight, we fabricated the LGP by injection molding of a zero-zero-birefringence polymer, poly(methyl methacrylate-co-2,2,2-trifluoroethyl methacrylate-co-benzyl methacrylate) (52: 42: 6 by mass) that is free of both orientational and photoelastic birefringence. The degree of polarization of light from the resulting backlight (average: 92.4%) was much higher than that from a backlight with a polycarbonate LGP (average: 8.0%) in the defined effective range of the backlight. A laser speckle pattern was observed but the speckle contrast on the output surface of the backlight was reduced from 68 to 10% by vibrating a diffuser sheet situated in front of the output surface of the LGP. We also manufactured a white surface light source [chromaticity (value: x, y) = (0:310, 0:314)] by mixing the outputs from three primary-color-emitting lasers in the backlight.     

Stereospecific Synthesis of a Dihydroxyethylene Isostere of Cyclohexylalanine Amide, (2S,3R,4S)-4-Amino-5-Cyclohexyl-1-Morpholino-2,3-Pentanediol(ACMP) from a Protected Sugar

ABSTRACT

A transition-state analogue of a renin inhibitor at the scissile site, a dihydroxyethylene isostere of cyclohexylalanine amide, (2S,3R,4S)-4-amino-5-cyclohexyl-1-morpholino-2,3-pentanediol(ACMP), was synthesized from 1,2:5,6-di-O-isopropylidene-α-D-allofuranose stereospecifically.     

A sensory evaluation of irradiated cookies made from flaxseed meal

The growing consumer demand for food with sensory quality and nutritional has called for research to develop new products with consumer acceptance as cookies made from flaxseed meal, that can be inserted in diet of celiacs. Celiac disease characterized by an inappropriate immune response to dietary proteins found in wheat, rye and barley (gluten and gliadin). It can affect anyone at any age and is more common in women. The celiac disease does not have cure and the only scientifically proven treatment is a gluten free diet. Irradiation as a decontamination method used for a many variety of foodstuffs, being very feasible, useful method to increase the shelf life, effective and environmental friendly without any sensory properties significant change. Sensory analyses were used to assess gluten-free bakery foods subjected to ionizing radiation sensory attributes.     

Adjacent- versus remote-site electron injection in TiO2 surfaces modified with binuclear ruthenium complexes

Nanocrystalline thin films of TiO2 cast on an optically transparent indium tin oxide glass were sensitized with ruthenium homo- and heterobinuclear complexes, [LL'Ru(BL)RuLL']n+ (n = 2, 3), where L and L' are 4,4'-dicarboxy-2,2'-bipyridine (dcb) and/or 2,2'-bipyridine (bpy) and BL is a rigid and linear heteroaromatic entity (tetrapyrido[3,2-a:2',3'-c:3",2"-h:2'",3'"-j]phenazine (tpphz) or 1,4-bis([1,10]phenanthroline[5,6-d]imidazol-2-yl)benzene (bfimbz)). The photophysical behavior of the RuII-RuII diads in solution indicated the occurrence of intercomponent energy transfer from the upper-lying Ru --> bpy charge-transfer (CT) excited state of the Ru(bpy)(2) moiety to the lower-lying Ru --> dcb CT excited state of the Ru(bpy)(dcb) (or Ru(dcb)(2)) subunit in the heterobinuclear complexes. These sensitizer diads adsorbed on nanostructured TiO2 surfaces in a perpendicular or parallel attachment mode. Adsorption was through the dcb ligands on one or both chromophoric subunits. The behavior of the adsorbed species was studied by nanosecond time-resolved transient absorption and emission spectroscopy, as well as by photocurrent measurements. In the TiO2-adsorbed samples where BL was bfimbz, the electron injection kinetics was very fast and could not be resolved because an electron is promoted from the metal center to the dcb ligand directly linked to the semiconductor. In the TiO2-adsorbed samples where BL was tpphz, for which, in the excited state, a BL localization of the lowest-lying metal-to-ligand charge transfer (MLCT) is observed, slower injection rates (9.5 x 10(7) s(-1) in [(bpy)(2)Ru(tpphz)Ru(bpy)(dcb(-))](3+)/TiO2 and 5.5 x 10(7) s(-1) in [(bpy)(dcb)Ru(tpphz)Ru(bpy)(dcb(-))](3+)/TiO2) were obtained. Among the systems, the heterotriad assembly [(bpy)(2)Ru(bfimbz)Ru(bpy)(dcb(2-))](2+)/TiO2 gave the best photovoltaic performance. In the first case, this was attributed to a fast electron injection initiated from a dcb-localized MLCT; in the second case, this is attributed to improved molecular orientation on the surface, which was due to rigidity and, at the same time, linearity of the heterotriad system, resulting in a slower charge recombination between the injected electron and the hole.     

Dual emission from rhenium(I) complexes induced by an interligand aromatic interaction

A series of rhenium(I) diimine complexes cis,trans-[Re(dmb)(CO)(2)(PR(1)R(2)R(3))(PR(4)R(5)R(6))](+) (dmb=4,4'-dimethyl-2,2'-bipyridine, R(n)=phenyl or alkyl), each of which bears two phosphine ligands with various numbers of phenyl groups, has been synthesized by using the photochemical ligand-substitution reaction. Detailed studies of the structural features, not only in the crystal but also in solution, indicate that the number of phenyl groups is a crucial factor in controlling the rotational conformation of the phosphine ligands, which in turn determines the extent of the π-π interaction between the aromatic diimine ligand and the phenyl group(s). The π-π interaction strongly affected both electrochemical and photophysical properties: 1) the oxidation power of the Re complex became stronger, 2) the lifetime of the excited state became longer, and 3) the Stokes shift between the (1) MLCT absorption band and emission from the corresponding (3) MLCT excited state became smaller. In particular, the diphenyl and triphenyl phosphine had much greater influence on the properties than the monophenyl phosphine ligand. Dual emission was observed from the different rotational conformers of the complexes with an intermediate number of phenyl groups in the phosphine ligands.     

New feature of delayed luminescence: preillumination-induced concavity and convexity in delayed luminescence decay curve in the green alga Pseudokirchneriella subcapitata

A new method for measuring delayed luminescence (delayed fluorescence) employs preillumination and a dark waiting period before normal excitation. The preillumination results in a concavity and a convexity in the decay curve in delayed luminescence in the green alga Pseudokirchneriella subcapitata. Formation of the concavity and the convexity is not affected by excitation wavelength (680 nm and 700 nm). However, the concavity and the convexity progressively decrease as the dark waiting period increases after preillumination. The formation of the concavity and the convexity was inhibited by exposure to the electron transport inhibitors DBMIB (644 μg/L, 2.0 μM) and Antimycin A (55 μg/L, 0.1 μM). Samples exposed to DBMIB exhibited noticeable reduction in the concavity, whereas samples exposed to Antimycin A exhibited pronounced reduction in the convexity. There is a possibility that the formation and disappearance of the concavity and the convexity are due to the reduction–oxidation state of the plastoquinone pool and the cyclic electron transport. We expect this method being useful in evaluating the effects of chemicals (particularly toxic chemicals) on photosynthetic reactions, and the method may also help to resolve questions regarding the source of long delayed luminescence.     

Chemical constituents from Sambucus adnata and their protein-tyrosine phosphatase 1B inhibitory activities

The MeOH extract from the whole plants of Sambucus adnata has shown significant protein-tyrosine phosphatase 1B (PTP1B) inhibitory activity. Chemical study on the extract resulted in the isolation of thirteen compounds, including a novel triterpene (1). The structure of 1 was determined to be 1α,3β-dihydroxy-urs-12-en-11-one-3-yl palmitate on the basis of extensive spectroscopic analyses. Among the isolated compounds, ursolic acid, oleanolic acid and (±)-boehmenan showed the most potent PTP1B inhibitory activity in vitro with the IC(50) values of 4.1, 14.4 and 43.5 μm, respectively. The kinetic analysis indicated that (±)-boehmenan inhibits PTP1B activity in a competitive manner.     

High‐thermally stable and high‐bandwidth graded index plastic optical fiber for vehicle networks

Radial refractive index profiles within the graded index plastic optical fiber (GI‐POF) is formed by adding a dopant to a polymer. This addition of the dopant significantly decreased the T_g of the polymer due to the plasticization. This disadvantage made the installation of the GI‐POF difficult, especially in vehicle networks in which high thermal stability is required. We have suggested 9‐bromophenanthrene (BPT) as a novel dopant induced less plasticization for poly(methyl methacrylate) (PMMA) than the conventional dopants. However, although the fabricated GI‐POF using BPT had high enough thermal stability for vehicle networks, the attenuation was 800 dB/km and it could not be used. This high attenuation was caused by contaminant in the fabrication process of fibers. In this study, we succeeded to fabricate a GI‐POF with low‐attenuation and high‐thermal stability using highly pure BPT. Its attenuation was improved to 240 dB/km at 650 nm, which was enough transparency for vehicle networks. The T_g of the GIPOF was improved to 107 °C from 90 °C. The thermal stability of the GI‐POF below 85 °C/dry and 75 °C/85%RH was demonstrated to be as high as that of the commercially available step index POF. The bandwidth of the GI‐POF could be estimated over 4.0 GHz for the 50‐m fiber. These results demonstrated that our GI‐POF should qualify to be used in vehicle network. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1464–1469, 2011