Reduction of elemental selenium by samarium diiodide: Selective synthesis of diorganyl selenides and diselenides

The reduction of elemental selenium by samarium diiodide led to selective formation of selenolate anion species (Se²⁻ and Se₂²⁻), the alkylation of which provided dialkyl selenides and diselenides, respectively, in excellent yields.     

NMR studies on the ligand exchange reactions between diaryl tellurides and phenyllithium: Detection of hypervalent triaryl tellurium ate complexes

Diaryl tellurides undergo rapid ligand exchange and disproportionation reactions on treatment with phenyllithium at −78°C. Triarylteliuranes [10-Te-3(C₃)]⁻ Li⁺ were identified as discrete intermediates during the reactions by ¹²⁵Te, ¹H, ¹³C, and CH-COSY NMR studies.     

Generation and stabilization of ultrafast optical pulse trains with monolithic mode-locked laser diodes

In this paper, we report on the generation and the stabilization of ultrafast optical pulse trains exceeding 100 GHz from monolithic mode-locked laser diodes (MLLDs) combined with some new techniques such as subharmonic synchronous mode-locking (SSML) and repetition-frequency multiplication (RFM) method. Key subjects to increase the pulse repetition frequencies of the MLLDs such as fast absorption recovery and harmonic mode-locking operation are discussed. 500 GHz optical pulse generation from a short-cavity, graded-index separated confinement heterostructure MLLD and THz-rate pulse generation by harmonic mode-locking are reported. We also demonstrate the stabilization of a 160 GHz MLLD by the SSML with subharmonic-frequency optical pulse injection and reveal that the SSML is very promising as a stabilization technique of the ultrafast MLLD beyond the limitations by the electronic device speed. A method to accurately measure the timing jitter of such ultrafast optical pulse train, all-optical down converting using a nonlinear optical device, is also presented. We also mention another choice for ultrafast optical pulse generation using the MLLD combined with a dispersive medium such as an optical fiber. We demonstrate here the generations of stable 84–256 GHz optical pulse trains by the RFM method of the MLLD stabilized by the SSML.     

Reflection of a pulse by multiple-dielectric layers

The reflection of a pulse by multiple-dielectric layers is treated theoretically. The reflected wave is obtained by expanding the reflection coefficient of an elementary plane wave in a series, including the special case for which total reflection occurs. The pulsed waves reflected by two-dielectric slabs are considered in detail both analytically and numerically. The effect of a carrier frequency of a pulse-modulated carrier wave on the reflected wave form is also discussed.     

Ruby ESR Over a Wide Frequency Range in the Millimeter Wave Region

The ESR of Cr³⁺ in dark ruby is measured using a high frequency ESR spectrometer with a wide frequency range which uses a gyrotron as the radiation source. For this purpose, GYROTRON FU- IV A developed at Fukui University was optimized for use in an ESR apparatus operating in the millimeter-wave range.The observed fine structure constant D for ruby is found to be D –5.728 GHz and the g-values g 1.981, g 1.982. Both the values of |D| and g are smaller than those obtained at lower frequencies by other work. Higher order terms of the spin hamiltonian are discussed in order to understand the ruby ESR results in this higher frequency range.     

Higher Harmonic Operations of Submillimeter Wave Gyrotrons (Gyrotron FU Series)

Higher harmonic operation of gyrotrons is necessary to obtain high frequencies. Some gyrotrons included in the Gyrotron FU series developed at Fukui University have achieved operation at the third and even fourth harmonics of the electron cyclotron frequency. The output lies in the millimeter to submillimeter wavelength range and the output powers are several watts to several tens of watts. In this paper, the gyrotrons and the conditions under which they operate are described in detail.     

Strategy for synthesis of the isoleucine conjugate of epi-jasmonic acid

The TES ether of 2-((1R,2S,3R)-3-hydroxy-2-((Z)-pent-2-enyl)cyclopentyl)acetic acid (5, equal to the reduction product of epi-jasmonic acid) derived from (1R,4S)-4-hydroxycyclopent-2-enyl acetate (19) in 13 steps was activated by using isobutyl chloroformate and was subjected to condensation with isoleucine at room temperature for 48 h. The product was desilylated and oxidized to the isoleucine conjugate of epi-jasmonic acid in 68% yield over three steps. Similarly, allo-isoleucine conjugate of epi-jasmonic acid and three isoleucine conjugates of ent-epi-jasmonic acid, jasmonic acid, and ent-jasmonic acid were synthesized.     

Fabrication of novel layer-by-layer assembly films composed of poly(lactic acid) and polylysine through cation-dipole interactions

Novel layer-by-layer (LbL) assembly films composed of poly( L-lysine) (PLL) and poly( D-lactic acid) (PDLA) were prepared by the alternate immersion of a gold substrate into an aqueous PLL solution and an acetonitrile solution of PDLA. The formation of the LbL assembly film was confirmed by quartz crystal microbalance (QCM) analysis, atomic force microscopy observation, and attenuated total reflection Fourier transform infrared spectroscopy measurement. The driving force responsible for the LbL assembly was determined by investigating the formation behavior of the LbL assembly under various conditions. The formation of the LbL assembly was not affected either by the stereochemistry of polylysine and poly(lactic acid) or by the addition of urea, which is known to inhibit hydrogen bonding interaction between polymers, into the aqueous PLL solution. The LbL assembly was also formed by the combination of PDLA and polycations other than polylysine, such as poly(diallyldimethylammonium chloride). On the other hand, the combination of PDLA and any polyanions such as poly(styrene sulfonate sodium salt) produced little corresponding LbL assembly. The increase in positive charge on the amino nitrogen atom of PLL enhanced the LbL assembly. These results suggest that the LbL assembly film composed of PLL and PDLA was fabricated by cation-dipole interactions between the positive charge on the amino nitrogen atom of PLL and the lone pairs of the carbonyl oxygen atom of PDLA.