Luminance and brightness field distribution of light guiding plate for backlight panel (BLP) by micro molding

This research investigates the luminance and the brightness field distribution of the microstructure of a light guiding plate (LGP) by micro injection molding (MIM) and micro injection‐compression molding (MICM). The process of manufacturing a LGP includes photo‐etching, MIM, MICM, and optical field measurement. The results show that the luminance of microstructure of LGPs produced using MICM is better than those made using MIM. The results also indicate that the most important processing parameter is the mold temperature for the luminance distribution of the LGP whether made by MIM or MICM. The maximum luminance of the LGP is 80 Nit (cd/m²) on micro molding. The brightness field distribution of the LGP made using MICM is more uniform than those made using MIM for the same processing parameters. MICM is a more suitable process than MIM for the fabrication of a LGP on a backlight panel (BLP). Copyright © 2008 John Wiley & Sons, Ltd.     

Accelerating charge transfer in a triphenylamine-subphthalocyanine donor-acceptor system

We have designed, synthesized and probed a dodecafluoro-subphthalocyaninato boron(III) unit, which bears a triphenylamine moiety in its axial position, as a novel electron donor-acceptor system.     

Thermal analysis of cellulose acetate modified with caprolactone

Cellulose acetate (CA) was modified with caprolactone (CL) under various reaction conditions in an internal mixer. The thermal behavior and relaxation transitions of the samples were determined by dynamic mechanical analysis and differential scanning calorimetry. Various relaxation transitions were detected in externally and internally modified cellulose acetate by DMTA. These were assigned to the glass transition of the main chain, to the movement of single glucose units and to hydroxymethyl groups. The β′ transition must belong to structural units larger than a single glucose ring and their formation must depend on sample preparation conditions. No transition could be assigned to grafted polycaprolactone (PCL) chains by DMTA. Contrary to other groups, we could not detect even the transitions of modified CA by DSC. Only the crystallization of oligomeric PCL homopolymer was observed mostly when it diffused to the surface of the sample.     

Lipschitzian retracts and curves as invariant sets

By an invariant set in a metric space we mean a non-empty compact set K such that K = ⋃ _i=1 ⁿ T _i (K) for some contractions T ₁, …, T _n of the space. We prove that, under not too restrictive conditions, the union of finitely many invariant sets is an invariant set. Hence we establish collage theorems for non-affine invariant sets in terms of Lipschitzian retracts. We show that any rectifiable curve is an invariant set though there is a simple arc which is not an invariant set.      

Complex formation processes of terminally protected peptides containing two or three histidyl residues. Characterization of the mixed metal complexes of peptides

Copper(ii), nickel(ii) and zinc(ii) complexes of the peptides Ac-HVVH-NH(2) and Ac-HAAHVVH-NH(2) have been studied by potentiometric, UV-vis, CD, EPR and NMR spectroscopic measurements. Both tetra and heptapeptides can form relatively stable macrochelates with copper(ii), nickel(ii) and zinc(ii) ions, in which the ligands are coordinated via the side-chain imidazole functions. Formation of the macrochelates slightly suppresses, but cannot prevent the copper(ii) and nickel(ii) ion promoted deprotonation and coordination of the amide functionalities. The overall stoichiometry of the major species is [MH(-3)L](-) with a 4N (= N(-),N(-),N(-),N(im)) coordination mode. In the case of Ac-HAAHVVH-NH(2), coordination isomers of this species can exist with a preference for copper(ii) or nickel(ii) binding at the internal histidyl residue. In the copper(ii)-Ac-HAAHVVH-NH(2) system, the presence of the two anchoring sites results in the formation of dinuclear complexes. The existence of these species requires the involvement of amide functions in metal binding. Both equilibrium and spectroscopic data support the fact that the copper(ii) ions of the dinuclear species are independent from each other providing a good chance for the formation of various mixed metal complexes. It was found that zinc(ii) is not able to significantly alter the copper(ii) binding of the heptapeptide, but it can occupy the uncoordinated histidyl sites. The formation of the copper(ii)-nickel(ii) mixed species was obtained in alkaline solutions and CD spectra suggest the statistical distribution of the two metal ions among the histidyl residues. The binding of HAAHVVH to palladium(ii) is exclusive below pH 8 and the mixed metal species of palladium(ii) and copper(ii) ions are formed only in slightly basic solutions.     

Efficient synthesis of 2-(trifluoromethyl)nicotinic acid derivatives from simple fluorinated precursors

Novel routes to 2-trifluoromethyl-nicotinic acid derivatives have been developed involving synthesis of the pyridine ring. These pyridyl compounds serve as key intermediates in the manufacture of the recently discovered COMT inhibitor, 3-(5-(3,4-dihydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-2-(trifluoromethyl)pyridine 1-oxide.     

A short, scalable synthesis of the carbocyclic core of the anti-angiogenic cortistatins from (+)-estrone by B-ring expansion

A rapid and scalable synthesis of the carbocyclic core of the potent antiangiogenic natural products, the cortistatins, is presented starting from readily available (+)-estrone. Key steps include a regio- and stereoselective benzylic cyanation and a Demjanov rearrangement.     

Copper-catalyzed synthesis of enantioenriched tetraarylethanes

Herein we report the asymmetric synthesis of 1,2-dipyridyl-1,2-diarylethanes via an unusual Cu(I)-catalyzed dimerization reaction. Subjection of a variety of enantioenriched substituted 2-pyridyl alcohols to a one-pot protocol generates the desired products in good yields and diastereoselectivities and with ee's up to >99%.