Growth and characterization of pyrene crystals on carbon nanofibers

Pyrene crystals were grown on carbon nanofibers (CNFs) by dispersing pyrene polycrystals and CNFs in water during ultrasonic irradiation, and they were characterized by scanning electron microscopy, X-ray diffractometry (XRD) and spectroscopy. The XRD measurements indicated that the orientation and size of the pyrene crystals on the CNF aggregates were different from that of the added pyrene polycrystals. Based on the spectroscopic properties of the pyrene crystals on the CNFs, the pyrene crystals on the CNF aggregates and on the individual CNFs were determined to be polycrystals and single crystals, respectively. These results indicate that pyrene crystals are produced on the CNFs by recrystallization of the added pyrene polycrystals and their crystal states depend on the aggregation state of the CNFs.     

Photon Trapping and the Enhancement of Electronic Excitation Energy Transfer Efficiency Caused by Colloidal Crystals

Summary: The efficiency of electronic excitation energy transfer from photoexcited fluorescein to rhodamine 6G is enhanced by 2.26 times in an exhaustively deionized colloidal silica suspension. This enhancement is caused by the photon trapping effects due to the Bragg reflection of colloidal crystals formed in the suspension. The lower enhancement efficiency of 1.41 times observed for rhodamine B as an acceptor is attributed to the inefficient spectral overlap between donor fluorescence and acceptor absorption bands.     

Synthesis and properties of optically active phosphine-boranes possessing an l-menthyloxy group

(SP)-9-Anthryl(l-menthyloxy)phenylphosphine-borane and (SP)-(1-l-menthyloxy)benzo[b]phosphole-borane were synthesized, and their structures were characterized by X-ray crystallographic analysis. The latter compound was reduced by lithium naphthalenide at −78°C with cleavage of the P O bond, and the subsequent reaction with electrophiles afforded the corresponding tertiary phosphine-boranes possessing good to excellent enantiomeric excesses.     

Recent progress of photo‐resin for rapid prototyping, “resin for stereolithography”

A main goal for manufacturing systems is to shorten lead‐time for the development of new products. An important challenge is to make sound decisions at early stages of product development where committed costs are low which leads us to obtain a lower total cost. This could mean that incurred costs are higher in the beginning where more work has to be done in terms of learning the market, developing the product and the production system. An important feature is to avoid changes at later stages where the incurred costs are high. The stereolithography using photo curable liquid resin is important for the manufacturing. The technology based on the stereolithography has been widely accepted due to the phenomena of spreading “Information Technology (IT)” and three‐dimensional computer aided design (3D CAD) system. The stereolithography technique has become very popular in the field of automotive, home‐electronics industries. In this paper the photo curable liquid resins for the stereolithography system are reviewed.