Safety Guide-Line and Requirements for Distributed Raman Amplification and its Applications to WDM Transmission Systems

This paper discusses optical safety issues in distributed Raman amplification systems. Given the extremely high pump powers, network service operators have critical issues for safety. This paper focuses on both “eye-hazard” and “fire-hazards”.     

Towards a Measurement of the n=2 Lamb Shift in Hydrogen-like Nitrogen Using an Electron Beam Ion Trap

Hyperfine Interactions - Using a 14C16O2 laser the 2s 1/2–2p 3/2 (fine structure – Lamb shift) transition has been induced in 14N6+ ions trapped in an electron beam ion trap. Prospects...     

Controlled radical polymerization of 2‐hydroxyethyl methacrylate initiated by photofunctional 2‐(N,N‐diethyldithiocarbamyl)isobutyric acid

We demonstrated that density functional theory calculations provide a reliable and quantitative prediction of the trends in C? S bond dissociation energies using several model compounds as photoinitiator. On the basis of this information, we designed a possible photofunctional initiator for the polymerization of hydrophilic vinyl monomers. Photopolymerization of 2‐hydroxyethyl methacrylate (HEMA) hydrophilic monomer was carried out in ethanol initiated by 2‐(N,N‐diethyldithiocarbamyl)isobutyric acid (DTCA) under UV irradiation. We performed the first‐order time‐conversion plots in this polymerization system, and the straight line in the semilogarithmic coordinates indicated first order in monomer. The molecular weight of the poly(2‐hydroxyethyl methacrylate) (PHEMA) increased with increasing conversion. The molecular weight distribution (M_w/M_n) of the PHEMA was about 1.5. Methyl methacrylate (MMA) could also be polymerized in a living fashion with such a PHEMA precursor as a macroinitiator because PHEMA exhibited a dithiocarbamate (DC) group at its terminal end. This system could be applied to the architecture of amphiphilic block copolymers. It was concluded that these polymerization systems proceeded with controlled radical mechanism. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 76–82, 2004     

Synthesis and peripheral substituent effects of bay-annulated indigo derivatives

In this study, indolo-naphthyridine-6,13-diones (5a–d) with four different peripheral substituents were prepared via bay-annulation reactions of indigo. The resulting compounds (5a–d) exhibited fluorescence in the red to near-IR region, while the parent indigo molecule showed no fluorescence. Although the peripheral substituents were oriented to the exterior of the π-conjugated system, the electronic structure affected the absorption and fluorescence spectra. Moreover, calculated molecular orbitals and absorption spectra successfully reproduced the experimental absorption spectra and cyclic voltammograms.     

Total Synthesis and Biological Evaluation of Siladenoserinol A and its Analogues

The total synthesis of siladenoserinol A, an inhibitor of the p53–Hdm2 interaction, has been achieved. AuCl₃‐catalyzed hydroalkoxylation of an alkynoate derivative smoothly and regioselectively proceeded to afford a bicycloketal in excellent yield. A glycerophosphocholine moiety was successfully introduced through the Horner–Wadsworth–Emmons reaction using an originally developed phosphonoacetate derivative. Finally, removal of the acid‐labile protecting groups, followed by regioselective sulfamate formation of the serinol moiety afforded the desired siladenoserinol A, and benzoyl and desulfamated analogues were also successfully synthesized. Biological evaluation showed that the sulfamate is essential for biological activity, and modification of the acyl group on the bicycloketal can improve the inhibitory activity against the p53–Hdm2 interaction.     

Nanotube foam prepared by gelatin gel as a template

It has been known that simply mixing single-walled carbon nanotubes (SWCNTs) in an aqueous solution of gelatin disperses SWCNTs well for a period of months. Gels made from the gelatin-SWCNT mixture are also stable and have a clear, black color. Scanning electron microscopy shows that gelatin molecules self-organize into a foamlike structure. All SWCNTs are embedded in the gelatin film that makes up the foam walls. Those SWCNTs belonging to one face of the foam cell cannot approach other faces to make van der Waals contact. Thus, the foam structure is associated with stabilization of the SWCNT dispersion. The gelatin can be removed thermally while maintaining the foam structure to give a sponge made of nanotube foams. This highly porous solid is electrically conducting and mechanically stable and can be used as a structural frame for composite materials.     

Asymmetric Michael reactions of α-substituted acetates with cyclic enones catalyzed by multifunctional chiral Ru amido complexes

Well-defined 16-electron chiral Ru amido complexes, Ru[(R,R)-diamine](η⁶-arene), efficiently catalyze asymmetric Michael additions of Michael donors to cyclic enones to give adducts in high yields and with excellent ee’s. β-Ketoesters or nitroacetate as Michael donors react with 2-cyclopentenone in toluene or t-butyl alcohol containing the Ru amido catalyst (S/C=50) to afford the Michael adduct in 99% yield and with up to 92% ee. The outcome of the reaction was delicately influenced by the structures of the diamine and arene ligands as well as reaction conditions.     

Umpolung of reactivity of allylsilane,allylgermane, and allylstannane via their reaction with thallium (III) salt: a new allylation reaction for aromatic compound

A new direct allylation of the aromatic compound has been developed. A combination of allylsilane, allylgermane, or allylstannane and thallium (III) trifluoroacetate gave rise to an allyl cationic species which was allowed to react with an aromatic compound, a nucleophile, to give allylation product(s) in good yields.     

Effect of positively charged short peptides on stability of cubic phases of monoolein/dioleoylphosphatidic acid mixtures

To elucidate the stability and phase transition of cubic phases of biomembranes with infinite periodic minimal surface is indispensable from biological and physicochemical aspects. In this report, we investigated the effect of positively charged peptide-3K (LLKKK) and poly(L-lysine) on the phase stability of monoolein (MO) membranes containing negatively charged dioleoylphosphatidic acid (DOPA) (i.e., DOPA/MO membranes) using small-angle X-ray scattering. At first, the effect of peptide-3K on 10% DOPA/90% MO membrane in excess water, which is in the Q229 phase, was investigated. At 3.4 mM peptide-3K, a Q229 to Q230 phase transition occurred, and at >3.4 mM peptide-3K, the membrane was in the Q230 phase. Poly(L-lysine) (M(w) 1K-4K) also induced the Q230 phase, but peptide-2K (LLKK) could not induce it in the same membrane. We also investigated the effect of peptide-3K on the multilamellar vesicle (MLV) of 25% DOPA/75% MO membrane, which is in L(alpha) phase. In the absence of peptide, the spacing of MLV was very large (11.3 nm), but at > or = 8 mM peptide-3K, it greatly decreased to a constant value (5.2 nm), irrespective of the peptide concentration, indicating that peptide-3K and the membranes form an electrostatically stabilized aggregation with low water content. Poly(L-lysine) also decreased greatly the spacing of the 25% DOPA/75% MO MLV, indicating the formation of a similar aggregation. To compare the effects of peptide-3K and poly(L-lysine) with that of osmotic stress on stability of the cubic phase, we investigated the effect of poly(ethylene glycol) with molecular weight 7500 (PEG-6K) on the phase stability of 10% DOPA/90% MO membrane. With an increase in PEG-6K concentration, i.e., with an increase in osmotic stress, the most stable phase changed as follows; Q229 (Schwartz's P surface) --> Q224 (D) --> Q230 (G). On the basis of these results, we discuss the mechanism of the effects of the positively charged short peptides (peptide-3K) and poly(L-lysine) on the structure and phase stability of DOPA/MO membranes.