Influence of the Polymer/Inorganic Filler Interface on the Mechanical,Thermal, and Flame Retardant Properties of Polypropylene/Magnesium Hydroxide Composites

The relationship between the interface structure and the macroscopic properties of composites composed of isotactic polypropylene (iPP) and magnesium hydroxide (MH) was investigated with a focus on mechanical properties, thermal stability, and flame retardancy. Surface treatment of MH was carried out using dodecanoic acid (DA) and dodecylphosphate (DP), both of which interacted with MH to form submonolayer coverages. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) revealed that both organic reagents adhere to the MH surface via ionic interactions. Even low amounts of organic reagents on the MH surface were sufficient to improve the mechanical, thermal, and flame retardant properties of the composites. The incorporation of 1.8 wt% of DP in (70/30) iPP/MH-DP composite decreased the peak heat release rate (PkHRR) to 39% compared with that of neat iPP. Since the effects of DA with the same dodecyl chains were not significant, it is concluded that the phosphate groups in DP provide flame retardancy.     

Novel Flavonoids in Dragon's Blood of Daemonorops draco

The three novel methylene bis[flavonoids] 1 – 3 , the novel 2‐flavene 4 , the new naturally occurring flavan 5 , and the new retro‐dihydrochalcone 6 were isolated from dragon's blood of Daemonorops draco, together with seven known compounds. The structures were elucidated by extensive 1D‐ and 2D‐NMR spectroscopic analysis.     

Two-dimensional observation of excited atoms and ions and excitation temperature in inductively coupled plasma using newly developed four channel spectrovideo camera

Abstract  

A four-channel spectrovideo camera was developed and applied to the measurement of spatially and spectrally resolved profiles of atomic and ionic emission in an inductively coupled plasma (ICP). Spatial distributions of argon and chromium atoms and iron ions in ICP were visualized successfully. The excitation temperature profiles of argon, chromium, and iron in ICP were also successfully constructed on the basis of the two-line method. The excitation temperature profiles obtained with a monochromator and the spectrovideo camera were in fairly good agreement.     

Gas permeation characteristics of a hydrogen selective supported silica membrane

A highly hydrogen permeable silica membrane, referred to as Nanosil, was obtained by chemical vapor deposition of a thin SiO₂ layer on a porous Vycor glass support. This composite membrane showed good permeance (10⁻⁸ mol m⁻² s⁻¹ Pa⁻¹) for the small gas molecules (He, Ne, and H₂) at 873 K with high selectivity (10⁴) over other larger gas molecules (CO₂, CO, and CH₄). The characteristics of gas transport on the Vycor and Nanosil membrane were investigated with several gas diffusion models. The experimental gas permeation data on Vycor glass could be explained by the occurrence of Knudsen diffusion in parallel with surface diffusion. The permeance of the small gas molecules (He, Ne, and H₂) on the Nanosil membrane was activated, and increased as temperature increased. However, this permeance was limited at high temperature because of the limited permeance on the Vycor support. The gas permeance on the deposited silica layer was obtained by applying a series analysis of gas permeation on the combined silica layer and Vycor support composite system. The order of permeance through the silica layer was He>H₂>Ne which was the same as that through vitreous silica glass, but occurred with lower activation energies. The order of permeation of these small gas molecules did not follow either mass or molecular size but could be explained using a statistical gas permeance model.     

New method to measure whole-wavelength transmittance of TCO substrates for thin-film silicon solar cells

High transmittance of transparent conductive oxide (TCO) substrates is one of the most important factors for achieving high efficiency in thin-film silicon solar cells. Immersion (IM) method with CH₂I₂ liquid is widely used for the evaluation of optical properties (transmittance, reflectance and absorption) for TCO substrates with textured surface in order to reduce the scattering at the TCO surface. However, in order to measure transmittance accurately, three problems have been found. (1) CH₂I₂ liquid itself absorbs the light in short wavelength region. (2) The transmittance around the absorption edge of CH₂I₂ liquids is very sensitive to its amount. (3) Scattering cannot be suppressed when the scattering surfaces are more than 2 surfaces (for example, TCO on reactive ion etching (RIE) processed glass). To overcome these problems, we proposed a new setup to measure optical properties of TCO substrates by holding the samples inside the integral sphere. As the results, we have confirmed that their absorption in all wavelength could be measured accurately and the transmittance measured by the new method was well consistent with the external quantum efficiency (EQE) of the fabricated cell while the transmittance measured with conventional IM method showed differently. Therefore, this new method could be a useful tool to evaluate TCO substrates for thin-film silicon solar cells.     

"ON-OFF" switching of europium complex luminescence coupled with a ligand redox process

A triarylamine-functionalized terpyridine ligand formed a highly coordinated complex with europium tris(β-diketonate), which displayed reversible 'ON-OFF' luminescence switching coupled with a ligand redox process of triarylamine/triarylaminium cations.     

Real-time propagation time-dependent density functional theory study on the ring-opening transformation of the photoexcited crystalline benzene

Mechanism of the ring-opening transformation in the photoexcited crystalline benzene is investigated on the femtosecond scale by a computational method based on the real-time propagation (RTP) time-dependent density functional theory (TDDFT). The excited-state dynamics of the benzene molecule is also examined not only for the distinction between the intrinsic properties of molecule and the intermolecular interaction but for the first validation using the vibration frequencies for the RTP-TDDFT approach. It is found that the vibration frequencies of the excited and ground states in the molecule are well reproduced. This demonstrates that the present method of time evolution using the Suzuki-Trotter-type split operator technique starting with the Franck-Condon state approximated by the occupation change of the Kohn-Sham orbitals is adequately accurate. For the crystalline benzene, we carried out the RTP-TDDFT simulations for two typical pressures. At both pressures, large swing of the C-H bonds and subsequent twist of the carbon ring occurs, leading to tetrahedral (sp3-like) C-H bonding. The nu4 and nu16 out-of-plane vibration modes of the benzene molecule are found mostly responsible for these motions, which is different from the mechanism proposed for the thermal ring-opening transformation occurring at higher pressure. Comparing the results between different pressures, we conclude that a certain increase of the intermolecular interaction is necessary to make seeds of the ring opening (e.g., radical site formation and breaking of the molecular character) even with the photoexcitation, while the hydrogen migration to fix them requires more free volume, which is consistent with the experimental observation that the transformation substantially proceeds on the decompression.     

Oxidative dehydrogenation of ethane over Cr/ZSM-5 catalysts using CO2 as an oxidant

Highly active catalysts for oxidative dehydrogenation of ethane with CO2 were characterized by temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), Fourier transform infrared (FTIR) spectroscopy, and X-ray absorption fine-structure (XAFS) analysis. In the active catalysts, Cr/H-ZSM-5 (SiO2/Al2O3 > 190), Cr6+ = O, or possibly Cr5+ = O was the catalytic species on the zeolite support. In contrast, little Cr6+ (or Cr5+) was detected in the less-active catalysts. The Cr6+ (or Cr5+) species was reduced to an octahedral Cr3+ species by treatment with ethane at 773 K, and the reduced Cr species was reoxidized to the Cr6+ (or Cr5+) species by treatment with CO2 at 673-773 K. The Cr redox cycle played an important role in the catalyst's high activity.     

Novel and efficient synthesis of cyanidin 3-O-beta-D-glucoside from (+)-catechin via a flav-3-en-3-ol as a key intermediate

[reaction: see text] A novel and efficient synthesis of cyanidin 3-O-beta-D-glucoside (1) was accomplished the first time by a biomimetic oxidation route. From (+)-catechin, 3-OH was glucosylated, and the 4-position of the nucleus was then oxidized and dehydrated to give the 5,7,3',4'-tetra-O-(tert-butyldimethylsilyl)flav-3-en-3-ol 3-O-glucoside (8) as a key intermediate. 8 was deprotected and oxidized under air in hydrogen chloride-MeOH to give 1.