Synthesis and properties of polycyclic quinones condensed with 1,6-methano[10]annulene

Two types of polycyclic quinones condensed with 1,6-methano[10]annulenes as type A: 1,6-methanonaphtho[2,3-c][10]annulene-7,12-dione 5a, and type B: 1,6-methanonaphtho[2,3-c][10]annulene-5,14-dione 18, bis(1,6-methano[10]annuleno[3,4-b; 3,4-g])anthracene-10,21-dione 20, 1,6-methanoanthraceno[2,3-c][10]annulene-5,16-dione 22, 1,6-methanotetraceno[2,3-c][10]annulene-6,17-dione 23, and 1,6-methano phenanthreno[2,3-c][10]annulene-5,6-dione 24 have been synthesized. The acene derivative 6 corresponding to that of 5a was synthesized by the reduction of quinone 5a. The physical, spectral, and chemical properties of these new compounds have been investigated.     

Growth and carrier dynamics in type II band alignment GaInAsSb/GaSb quantum well structure

Using time-resolved photoluminescence we have investigated the As mole fraction-dependent change from type I to type II band alignments in GaInAsSb/GaSb multiple quantum well structures grown by molecular beam epitaxy (MBE). The decay time becomes longer with increasing As mole fraction of the quantum well region and the time for type II indirect transition is about 1 ns. Relatively high efficiency of indirect radiative transition is explained by the strong enhancement of the overlap of the electron and hole wave functions.     

Synthesis and properties of polycyclic quinones condensed with 1,6-methano[10]annulene

Two types of polycyclic quinones condensed with 1,6-methano[10]annulenes as type A: 1,6-methanonaphtho[2,3-c][10]annulene-7,12-dione 5a, and type B: 1,6-methanonaphtho[2,3-c][10]annulene-5,14-dione 18, bis(1,6-methano[10]annuleno[3,4-b; 3,4-g])anthracene-10,21-dione 20, 1,6-methanoanthraceno[2,3-c][10]annulene-5,16-dione 22, 1,6-methanotetraceno[2,3-c][10]annulene-6,17-dione 23, and 1,6-methano phenanthreno[2,3-c][10]annulene-5,6-dione 24 have been synthesized. The acene derivative 6 corresponding to that of 5a was synthesized by the reduction of quinone 5a. The physical, spectral, and chemical properties of these new compounds have been investigated.     

Rapid synthesis of Ag@Ni core-shell nanoparticles using a microwave-polyol method

Mixtures of AgNO₃ and NiSO₄·6H₂O, NiCl₂·6H₂O, or Ni(NO₃)₂·6H₂O were reduced in ethylene glycol (EG) in the presence of NaOH and poly(vinylpyrrolidone) (PVP) under microwave (MW) heating for 10 min. Then, we succeeded in the synthesis of Ag core-Ni shell nanoparticles, denoted as Ag@Ni, in high yield. The formation of Ag@Ni particles was confirmed using energy dispersed X-ray spectroscopic (EDS) measurements and selected area electron diffraction (SAED) patterns. The growth mechanism of Ag@Ni is discussed. The UV-Vis spectra of Ag@Ni were similar to those of Ni particles.     

Temperature dependence of dielectric permittivity of perovskite-type artificial superlattices

Perovskite-type BaTiO(3)/SrTiO(3) (BTO/STO) artificial superlattices were fabricated by the molecular beam epitaxy method. The X-Ray diffraction (XRD) profiles and reflection, high-energy, electron diffraction (RHEED) oscillations during the growth of superlattices indicated that crystalline orientation toward [001] direction and two-dimensional layer-by-layer growth were achieved. The capacitance, dielectric loss tangent, and complex admittance were measured up to 145 degrees C and up to the frequency of 100 MHz with the microplaner interdigital electrodes. Dielectric permittivity of superlattices was evaluated from the complex admittance with an electromagnetic field analysis as a function of temperature. The [BTO(10)/STO(10)](4) superlattice showed the enormous relative permittivity of 19,000 at room temperature and the dielectric relaxation was observed. The linear relations in the charge versus voltage curves were observed in these superlattices, and the shape of Q-V curves were not changed as a function of temperature. Temperature dependence of dielectric properties of the BTO/STO superlattices was evaluated. It was found that the BTO/STO superlattices did not show a peak in the dielectric permittivity versus temperature curve, which was different from the behavior of BTO-STO bulk ceramics and normal thin films. These results strongly supported that the high permittivity of the superlattices was caused by temperature-stable anisotropic strains induced in the superlattices.     

Nontrivial polarization shaping of femtosecond pulses by reference to the results of dual-channel spectral interferometry

Adaptive shaping of time-dependent polarization pulses is performed by reference to the analyzed results of dual-channel spectral interferometry. The desired pulses can be generated only by use of such a polarization-characterization technique. We demonstrate the generation of shaped femtosecond pulses whose ellipticity increases at a constant rate. The relative error between the shaped pulse and the target pulse is less than 6% over the main part of the pulse. Shaped time-dependent polarization pulses have many potential applications.     

Fabrication of diamond-like carbon film on rubber by T-shape filtered-arc-deposition under the influence of various ambient gases

Diamond-like carbon (DLC) films were prepared on rubber substrates using T-shape filtered-arc-deposition (T-FAD), which effectively removes the macrodroplets emitted from the graphite cathode spot from the processing plasma. In the present study, the influence of ambient gas (no gas, Ar, H₂, C₂H₂, C₂H₄, CH₄) was investigated. The DLC films adhered well to the rubber substrate. When the substrate was stretched, the small DLC islands were separated and clefs were opened. The deposition rate on rubber was approximately twice higher than that on a Si substrate. When hydrocarbon gas was introduced as an ambient gas, the deposition rate became higher than that for no gas and H₂ gas. In the cases of C₂H₄ and CH₄ gases, the DLC film was considered to contain a considerable amount of hydrogen. When C₂H₂ gas was used, the highest deposition rate with less surface roughness was achieved.     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Design of stabilized digital inverse systems

As is well known, due to the existence of unstable limiting zeros and/or the minimum phase property of continuous-time systems, there are many cases that the discretized systems are of non-minimum phase. In this case, it is impossible to construct a stable digital inverse by usual methods. However, in this paper, we will show that if the inter-sample output is used in the design, one can always construct a stable digital inverse system.