Shape modeling of mineral dust particles for light-scattering calculations using the spatial Poisson-Voronoi tessellation

We present a shape model of mineral dust particles for use in light-scattering calculations. A spatial Poisson-Voronoi tessellation was applied to simulate the aggregate structure and, therefore, the rough surface of the mineral particles. To develop the shape model, we took into account statistics of shape parameters derived from the cross-sectional areas, maximum dimensions, and perimeters of field-collected dust particles. Light-scattering properties of the modeled Voronoi aggregates were examined by the finite-difference time-domain (FDTD) method. The results of randomly oriented scattering properties agreed with previously reported laboratory measurements of mineral dust particles.     

An unexpected chelate conformation in trans‐[(R)‐N,N′‐bis(α‐phenyl­salicyl­idene)­propane‐1,2‐diaminato(2–)]­bis(1‐methyl‐1H‐imidazole‐κN3)­cobalt(III) perchlorate

The title compound, [Co(C₂₉H₂₄N₂O₂)(C₄H₆N₂)₂]ClO₄, contains an optically active tetradentate Schiff base ligand in an equatorial plane and two 1‐methyl­imidazole ligands at apical positions. The central N—C—C—N chelate ring of the Schiff base ligand has an envelope structure with a λ conformation, which is different from the solution structure predicted from circular dichroism and ¹H NMR spectra.     

Neutron and X-ray diffraction studies on the Tb2Ni3Si5 single crystal

Neutron and X-ray diffraction studies on the Tb₂Ni₃Si₅ single crystal have been done to investigate its crystal modulation and magnetic properties. The modulated single crystal is constructed by the TbNiSi₂ (CeNiSi₂-type Cmcm) and the Tb₂Ni₃Si₅ (U₂Co₃Si₅-type Ibam) lattices. The relationship between the two lattices is described as direction of the b₁₁₂-axis coincides with the a₂₃₅-axis. The crystal modulation gives significant effects on magnetism. Each of the two lattices takes complex antiferromagnetism with multiplex propagation vectors.     

A facile formation of cyclic selenuranes and a cyclic selenurane oxide in the reaction of 2-methylseleno- and 2-phenylselenobenzoic acids and their derivatives with t-butyl hydroperoxide

The reaction of 2-methylselenobenzoic acid with 1,1′-carbonyldiimidazole followed by addition of t-butyl hydroperoxide gave cyclic selenuranes $\text{2a}$ and $\text{3a}$, suggesting the intramolecular insertion of the neighboring selenium atom into the OO bond of t-butyl 2-methylselenoperoxybenzoate. In the reaction of 2-phenylselenobenzoyl chloride with t-butyl hydroperoxide, cyclic selenurane $\text{2b}$ and the oxide $\text{7}$ were obtained.     

The Wittig rearrangement of fluorenyl ethers in two-phase system

The Wittig rearrangement of fluorenyl ethers by the use of potassium hydroxide as base in solid phase was readily effected by crown ethers and onium salts, while diamines moderately catalyzed the reaction.     

On the blue-colored species,possibly assignable to a radical cation,formed by the aromatic hydrocarbon–sulfur dioxide–oxygen system: The polymerization of olefins initiated by aromatic hydrocarbons–oxygen in liquid sulfur dioxide

It was found that styrene in liquid sulfur dioxide polymerizes, giving polystyrene readily and quantitatively by addition of such aromatic hydrocarbons as anthracene and trans- or cis-stilbene in the presence of oxygen, and the polymerization proceeds via a cationic process. The observations on the electronic spectra and kinetics in the system suggested that the polymerization was initiated by an electron transfer from the aromatic hydrocarbon to oxygen, followed by the formation of styrene radical cation. Supporting evidence of the radical cation is that 1,1-diphenylethylene in liquid sulfur dioxide in the presence of oxygen shows a peak at λ_max = 605 mμ and reacts to give benzophenone and 1,1,3,3-tetraphenyl-butene-1, which are eliminated by addition of a radical or cation inhibitor.     

Fluorescent additive for estimation of compatibility of polyester blend by imipramine-containing polymer

The effects of adding imipramine-containing polymer (PImip-Fl) in two kinds of polyester/lysine triisocyanate (LTI) blends were investigated. PImip-Fl was prepared by Suzuki–Miyaura coupling reaction of dibromoimipramine hydrochloride and dioctylfluorene diboronic acid. The addition of PImip-Fl gave fluorescence to resins [poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL)], and its fluorescent maximum wavelength (λ_max) depended on the resin. PImip-Fl was used as a functional additive for the estimation of compatibility of PLA/PCL blend composite. The addition of LTI to the resins/PImip-Fl blend composites afforded a shorter wavelength shift of the fluorescent λ_max. This suggested that the method using PImip-Fl is adaptive for the estimation of compatibility of the blend composite.     

Photoreversible Gelation of a Triblock Copolymer in an Ionic Liquid

The reversible micellization and sol–gel transition of block copolymer solutions in an ionic liquid (IL) triggered by a photostimulus is described. The ABA triblock copolymer employed, denoted P(AzoMA‐r‐NIPAm)‐b‐PEO‐b‐P(AzoMA‐r‐NIPAm)), has a B block composed of an IL‐soluble poly(ethylene oxide) (PEO). The A block consists of a random copolymer including thermosensitive N‐isopropylacrylamide (NIPAm) units and a methacrylate with an azobenzene chromophore in the side chain (AzoMA). A phototriggered reversible unimer‐to‐micelle transition of a dilute ABA triblock copolymer (1 wt %) was observed in an IL, 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([C₄mim]PF₆), at an intermediate “bistable” temperature (50 °C). The system underwent a reversible sol–gel transition cycle at the bistable temperature (53 °C), with reversible association/fragmentation of the polymer network resulting from the phototriggered self‐assembly of the ABA triblock copolymer (20 wt %) in [C₄mim]PF₆.     

Multi-sideband Generation in a Femtosecond Cr4+:YAG Laser

We describe the behavior of multi-sidebands in a self-mode-locked femtosecond Cr⁴⁺:YAG laser operating near 1.54 μm. Stokes and anti-Stokes sideband components are extended over 20 THz around the center frequency. An interesting feature here is that when the spectral width of the mode-locked pulse is increased, the specific Stokes sideband near 1.65 μm (a shift of 13.5 THz) is strongly enhanced due to an induced-Raman process in the laser rod. The measured frequency shifts for all sidebands are well explained by four-wave-mixing processes in the laser rod, accompanied by the resonance effect of the soliton and dispersive wave, both of which are affected mainly by cavity dispersions.