Vertex operator algebras, extended diagram, and McKay's observation on the Monster simple group

We study McKay's observation on the Monster simple group, which relates the -involutions of the Monster simple group to the extended diagram, using the theory of vertex operator algebras (VOAs). We first consider the sublattices of the lattice obtained by removing one node from the extended diagram at each time. We then construct a certain coset (or commutant) subalgebra associated with in the lattice VOA . There are two natural conformal vectors of central charge in such that their inner product is exactly the value predicted by Conway (1985). The Griess algebra of coincides with the algebra described in his Table 3. There is a canonical automorphism of of order . Such an automorphism can be extended to the Leech lattice VOA , and it is in fact a product of two Miyamoto involutions. In the sequel (2005) to this article, the properties of will be discussed in detail. It is expected that if is actually contained in the Moonshine VOA , the product of two Miyamoto involutions is in the desired conjugacy class of the Monster simple group.

     

High-pressure subsonic mode operation of chemical oxygen-iodine laser

A new regime of chemical oxygen-iodine laser (COIL), high-pressure subsonic mode operation, was demonstrated using a jet-type singlet oxygen generator (SOG). The laser output power of 342 W with chemical efficiency of 20.9% was obtained at the Cl₂ flow rate of 18 mmol/s and the operating pressure of 6.4 Torr in the laser cavity. The specific energy was 3.1 J/l which was four times higher than our supersonic device, and was comparable to the highest value for the supersonic regime. The experimental results were in good agreement with the numerical simulation results. Received: 26 February 1999 / Revised version: 13 July 1999 / Published online: 30 November 1999     

Synthesis of Block Copolymers with a Pentasilane Core

We report a new method for the synthesis of block copolymers with a pentasilane core by the polymerization of alkyl methacrylate monomers using the pentasilyl dianion as an initiator. The polymerization proceeded with living features and yielded the corresponding block copolymers with controlled molecular weights. The amphiphilic block copolymer was obtained by the polymer reaction, and it formed sphere‐like aggregates in MeOH/H₂O solution.

     

Enhanced effective mass in doped SrTiO3 and related perovskites

The effective mass is one of the main factors determining the Seebeck coefficient and electrical conductivity of thermo-electrics. In this ab-initio LDA-GGA study the effective mass is estimated from the curvature of electronic bands by one-band-approximation and is in excellent agreement with experimental data of Nb- and La-doped SrTiO₃. It is clarified that the deformation of SrTiO₃ crystals has a significant influence on the bandgap, effective electronic DOS-mass and band-mass, but the electronic effect due to the e_g-band flattening near the Γ-point due to Nb-doping up to 0.2 at% is the main factor for the effective mass increase. Doping of La shows a linear decrease of the effective mass; this can be explained by the different surroundings of A- and B-sites in perovskite. Substitution with other elements such as Ba on the A-site and V on the B-site in SrTiO₃ increases the effective mass as well.     

High repetition rate laser pulses amplified by Nd/Cr:YAG ceramic amplifier under CW arc-lamp-light pumping

Laser pulses with high repetitive rate generated from a Q-switch microchip Nd:YAG oscillator were amplified by Active mirror composed of Nd/Cr:YAG ceramic pumped by CW arc-lamp. The laser pulses were amplified, and saturation of averaged output laser power was observed. Repetitive ratio of injected laser pulses was changed from 20 to 100 kHz. Averaged output laser power and gain were measured, and gain coefficient and power-extraction efficiency were evaluated. Output laser power was calculated and compared to experimentally measured one, and the calculated results are consistent with the experimental ones. For amplification of laser pulses with high repetitive ratio, this laser material can realize very high laser gain with low pumping power density and high optical-optical conversion efficiency under CW-lamp-light pumping.     

Tuning of Electronic Properties of Single‐Walled Carbon Nanotubes under Homogenous Conditions

Reversible and non‐bonding interaction between SWNTs and ODCB is observed from the analyses of visible near‐infrared absorption data and Raman spectroscopies (see spectra). The solvent effect on SWNTs effectively controls the electronic structure of SWNTs under homogeneous conditions.

     

Reaction of the acetals with TESOTf-base combination; speculation of the intermediates and efficient mixed acetal formation

We report here unexpected highly chemoselective deprotection of the acetals from aldehydes. Treatment of acetal compounds from aldehydes with TESOTf-2,6-lutidine or TESOTf-2,4,6-collidine in CH2Cl2 at 0 degrees C followed by H2O workup at the same temperature caused the conversion of the acetal functions to aldehyde functions. The reaction had generality and was applied to many acetal compounds. Study using various bases revealed the reaction and reached the best combination of TESOTf-base. It was very mild and highly chemoselective and proceeded under weakly basic conditions. Then, many functional groups such as allyl alcohol, silyl ether, acetate, methyl ether, triphenylmethyl (Tr) ether, 1,3-dithiolane, methyl ester, and tert-butyl ester could survive under these conditions. Furthermore, this methodology could selectively deprotect the acetals in the presence of ketals as the most characteristic feature, although this chemoselectivity is difficult to achieve by other previously reported methods. A detailed study of the reaction including MS and NMR studies revealed the reaction mechanism for determining the structures of the intermediates, pyridinium-type salts. These intermediates had a weak electrophilicity and were successfully applied to the efficient formation of the mixed acetals in high yields.     

Mode of interaction of amphiphilic alpha-helical peptide with phosphatidylcholines at the air-water interface

Surface pressure (pi)-, surface potential (deltaV)-, and dipole moment (mu(perpendicular))-area (A) isotherms and morphological behavior were examined for monolayers of a newly designed 18-mer amphiphilic alpha-helical peptide (Hel 13-5), DPPC, and DPPC/egg-PC (1:1) and their combinations by the Wilhelmy method, ionizing electrode method, fluorescence microscopy (FM), and atomic force microscopy (AFM). The newly designed Hel 13-5 showed rapid adsorption into the air-liquid interface to form interfacial films such as a SP-B function. Regardless of the composition and constituents in their multicomponent system of DPPC/egg-PC, the collapse pressure (pi(c); approximately 42 mN m(-1)) was constant, implying that Hel 13-5 with the fluid composition of egg-PC is squeezed out of Hel 13-5/DPPC/egg-PC monolayers accompanying a two- to three-dimensional phase transformation. FM showed that adding a small amount of Hel 13-5 to DPPC induced a dispersed pattern of ordered domains with a "moth-eaten" appearance, whereas shrinkage of ordered domains in size occurred for the DPPC/egg-PC mixture with Hel 13-5. Furthermore, AFM indicated that (i) the intermediate phase was formed in pure Hel 13-5 systems between monolayer states and excluded nanoparticles, (ii) protrusions necessarily located on DPPC monolayers, and (iii) beyond the collapse pressure of Hel 13-5, Hel 13-5 was squeezed out of the system into the aqueous subphase. Furthermore, hysteresis curves of these systems nicely resemble those of the DPPC/SP-B and DPPC/SP-C mixtures reported before.     

Mode of interaction of hydrophobic amphiphilic alpha-helical peptide/dipalmitoylphosphatidylcholine with phosphatidylglycerol or palmitic acid at the air-water interface

Surface pressure (pi)-, surface potential (DeltaV)-, dipole moment (mu( perpendicular))-area (A) isotherms and morphological behavior at the air-water interface were obtained for multicomponent monolayers of two different systems for dipalmitoylphosphatidylcholine (DPPC)/egg-phosphatidylglycerol (PG) (= 68:22, by weight)/Hel 13-5 and DPPC/palmitic acid (PA) (= 90:9, by weight)/Hel 13-5 (Hel 13-5 is a newly designed 18-mer amphiphilic alpha-helical peptide with 13 hydrophobic and 5 hydrophilic amino acid residues). The phase behavior of these model systems was investigated on a subsolution of 0.02 M tris(hydroxymethyl)aminomethane (Tris) buffer (pH 8.4) with 0.13 M NaCl at 298.2 K by employing the Wilhelmy method, the ionizing electrode method, and fluorescence microscopy. Especially, the present study focuses on the interfacial effect of the addition of Hel 13-5 on two binary systems, DPPC/egg-PG and DPPC/PA monolayers, as the substitute for pulmonary surfactant proteins, and on the respective roles of PG and PA for the monolayers in the three-component systems. Constant kink points ( approximately 42 mN m(-1)) clearly appear on the pi-A isotherms, independent of the compositions in the ternary systems, which corresponds to the Hel 13-5 collapse pressure similar to that of SP-B and SP-C as functions in multicomponent monolayers. This implies that Hel 13-5 is squeezed out of ternary monolayers above approximately 42 mN m(-1), resulting in two- to three-dimensional phase transformation. Furthermore, Langmuir isotherms clearly show that Hel 13-5 with egg-PG is squeezed out of the DPPC/egg-PG/Hel 13-5 system, whereas only Hel 13-5 is squeezed out of the DPPC/PA/Hel 13-5 system. Cyclic compression and expansion isotherms of these systems were carried out to confirm the spreading and respreading capacities. In addition, the interfacial behavior of the ternary mixtures has been analyzed by the additivity rule. Morphological examinations and comparisons have verified the interactions of Hel 13-5 with the representative miscible mixture (DPPC/PA system) by fluorescence microscopy. Consequently, distinct morphological variations corresponding to the squeeze-out behavior are observed as a fluorescent contrast recovery. Herein, a new mechanism of the refluorescent phenomenon is proposed by varying the surface composition of Hel 13-5.     

Langmuir monolayer properties of the fluorinated-hydrogenated hybrid amphiphiles with dipalmitoylphosphatidylcholine (DPPC)

Surface pressure–area (π–A), surface potential–area (ΔV–A), and dipole moment–area (μ–A) isotherms were obtained for the Langmuir monolayer of two fluorinated-hydrogenated hybrid amphiphiles (sodium phenyl 1-[(4-perfluorohexyl)-phenyl]-1-hexylphosphate (F6PH5PPhNa) and (sodium phenyl 1-[(4-perfluorooctyl)-phenyl]-1-hexylphosphate (F8PH5PPhNa)), DPPC and their two-component systems at the air/water interface. Monolayers spread on 0.02 M Tris buffer solution (pH 7.4) with 0.13 M NaCl at 298.2 K were investigated by the Wilhelmy method, ionizing electrode method and fluorescence microscopy. Moreover, the miscibility of two components was examined by plotting the variation of the molecular area and the surface potential as a function of the molar fraction for the fluorinated-hydrogenated hybrid amphiphiles on the basis of the additivity rule. The miscibility of the monlayers was also examined by construction of two-dimensional phase diagrams. Furthermore, assuming the regular surface mixture, the Joos equation for analysis of the collapse pressure of two-component monolayers allowed calculation of the interaction parameter (ξ) and the interaction energy (−Δ) between the fluorinated-hydrogenated hybrid amphiphiles and DPPC. The observations by a fluorescence microscopy also supported our interpretation as for the miscibility in the monolayer state. Comparing the monolayer behavior between the two binary systems, no remarkable difference was found among various aspects. Among the two combinations, the mole fraction dependence in monlayer properties was commonly classified into two ranges: 0 ≤ X ≤ 0.3 and 0.3 < X ≤ 1. Dependence of the chain length of fluorinated part was reflected for the molecular packing and surface potential.