Monolayer assemblies of a sandwich-type double-decker porphyrin complex of cerium with an additional pendant porphyrin unit

We have prepared a novel sandwich-type double-decker porphyrin complex with cerium, in which one of the porphyrins has long alkyl chains and the other has a pendant free-base porphyrin unit. The preparation of the complex was achieved with a Sonogashira coupling reaction between a preformed double-decker complex bearing an ethynyl moiety and an iodophenyl porphyrin. This complex forms moderately ordered self-assembled monolayers at the interface of 1-phenyloctane and highly oriented pyrolytic graphite. STM images with submolecular resolution revealed that the double-decker complexes form monolayers through adsorption of the alkyl-substituted porphyrin unit, presenting the other porphyrin having the additional porphyrin unit to the solution. All molecules are oriented in the same direction within single ordered domains. The double-decker complex and the corresponding free-base porphyrin form mixed monolayers due to their common adsorbing group and the matching unit cell parameters. The high spots for the double-decker cores are accompanied by lower spots, which can be assigned as the pendant free-base porphyrin units, revealing that the double-decker complexes predominantly take perpendicular orientation, in which the additional porphyrin unit orients perpendicular to the molecular row. Both the double-decker complex and the free-base porphyrin adsorb on the surface initially after the mixture was deposited, but the double-decker complex is gradually replaced by free-base porphyrin toward the thermodynamically stable assembly, in which the free-base porphyrin predominates. This behavior is unique to this particular complex among some analogous complexes with the same adsorbing group, which implies that groups not directly involved in adsorption may have profound effects on the adsorption and assembling properties of the molecule.     

Growth of crack-free lithium tetraborate (Li2B4O7) single crystals

Abstract

The mode of occurrence and the origin of cracking of lithium tetraborate (Li₂B₄O₇) during growth by CZ method have been investigated. It is considered that crystal cracking can be divided into two main modes of occurrence. Each origin of cracking have been examined; 3-inch-diameter crack-free Li₂B₄O₇ have been successfully grown.     

A flexible 2.1‐in. active‐matrix electrophoretic display with high resolution and a thickness of 100 μm

Abstract— A paper‐thin QVGA, flexible 2.1‐in. active‐matrix electrophoretic display (AMEPD) that features 100‐μm thick and a 192‐ppi resolution has been developed. An LTPS‐TFT backplane with integrated peripheral driver circuits was first fabricated on a glass substrate and then transferred to a very thin (30‐μm) plastic film by employing surface‐free technology by laser ablation/annealing (SUFTLA®). A micro‐encapsulated electrophoretic imaging sheet was laminated on the backplane. A supporting substrate was used to support the LTPS‐TFT backplane. Fine images were successfully displayed on the rollable AM‐EPD. The integrated driver circuits dramatically reduce the number of external connection terminals, thus easily boosting the reliability of electrical connections even on such a thin plastic film.     

The Cyclandelate Reference Standard (Control 931) of the National Institute of Health Sciences

Raw thiamine hydrochloride material was tested for preparation of the "Thiamine Hydrochloride Reference Standard (Control 931)". Analytical data obtained were as follows: melting point, 242.7 degrees C (decomposition); infrared spectrum, the same as that of the JP Thiamine Hydrochloride Reference Standard; thin-layer chromatography, one impurity was detected; high-performance liquid chromatography (HPLC), a trace amount of one impurity was detected; assay results, 100.4% by UV spectrophotometry and 100.0% by HPLC, respectively. Based on the above findings, the raw material was authorized as the JP Thiamine Hydrochloride Reference Standard (Control 931).     

Morphophysiological and Proteomic Responses on Plants of Irradiation with Electromagnetic Waves

Electromagnetic energy is the backbone of wireless communication systems, and its progressive use has resulted in impacts on a wide range of biological systems. The consequences of electromagnetic energy absorption on plants are insufficiently addressed. In the agricultural area, electromagnetic-wave irradiation has been used to develop crop varieties, manage insect pests, monitor fertilizer efficiency, and preserve agricultural produce. According to different frequencies and wavelengths, electromagnetic waves are typically divided into eight spectral bands, including audio waves, radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. In this review, among these electromagnetic waves, effects of millimeter waves, ultraviolet, and gamma rays on plants are outlined, and their response mechanisms in plants through proteomic approaches are summarized. Furthermore, remarkable advancements of irradiating plants with electromagnetic waves, especially ultraviolet, are addressed, which shed light on future research in the electromagnetic field.     

Stabilization of two families of critical targets for hyperthermic cell killing and acquired thermotolerance of yeast cells

Hyperthermic cell killing profiles of Saccharomyces cerevisiae cells were biphasic and a shoulder (phase 1) was followed by an exponential killing (phase 2). Assuming that (i) the rate of thermal damage in particular macromolecules or their assemblies limits the rate of hyperthermic cell killing (the critical target model), and (ii) the damages of two families of targets are lethal independently, we built a ‘dual critical target model’ in order to interpret the biphasic cell killing. Time-courses of temperature-programmed fractional survival were traced for S. cerevisiae cells in exponentially growing phase, heat shocked, and in stationary phase. Non-linear curve-fitting of the time-courses by using the dual critial target model provided the Arrhenius parameters of denaturation of the two families of targets. The cells were killed more slowly in phase 1 than in phase 2. Arrest in stationary phase, not heat shock, stabilizes the family of targets that is critical to phase 1 death. On the other hand, both heat-shock response and arrest in stationary phase stabilizes the other family of targets that, in addition to the previous one, is responsible for phase 2 death. © 1998 John Wiley & Sons, Ltd.     

Fluorine uptake into human enamel around fluoride-containing dental materials during cariogenic pH cycling

Using PIGE (Proton Induced Gamma Emission) technique at TARRI (Takasaki Advanced Radiation Research Institute), Japan, we measured fluorine (F) uptake into the tooth enamel around two fluoride-containing materials during caries progression using pH cycling. Class V cavities in extracted human teeth were drilled and filled with fluoride-containing materials (i.e. “Fuji IX” (FN) and “UniFil flow with MEGA bond” (UF)) and a non-fluoride-containing material (i.e. “SOLARE with MEGA bond” (SO)). Three 120 μm longitudinal sections including the filling material were obtained from each tooth. In order to simulate daily acid attack occurring in the oral cavity, the pH cycling (pH 6.8–4.5) was carried out for 1, 3 and 5 weeks, separately. After pH cycling, the caries progression in all specimens was observed using transverse microradiography (TMR). The F and calcium distributions of the specimens were evaluated using PIGE and PIXE techniques. The F distribution of the specimens clearly showed the F uptake from FN into enamel adjacent to the filling material, while the F uptakes from UF and SO were not detected. For UF, the MEGA bond (non-fluoride-containing) between the tooth and UniFil flow interfered with the F absorption into the tooth. For FN, the amount of F uptake into the subsurface enamel increased during pH cycling. The amount of F uptake in 5-week pH cycling had significantly higher value compared to those in 1- and 3-week pH cycling. For UF and SO, there were no significant differences between the different durations of pH cycling.Among fluoride-containing materials, there were some differences in the F uptake with increased pH cycling, which could possibly lead to obtaining difference in clinical performance. The data obtained using PIGE and PIXE techniques were useful in understanding the benefit of fluorine by means of fluoride-containing material for preventing caries.     

Structure and Photocatalytic Activity of Iron Oxide Nanotubes Prepared from Ferritin

We report structure and photocatalytic activity of solid nanotubes comprising iron oxide (hematite, α-Fe₂O₃) nanoparticles. The initial precursor cylinders were prepared by alternating layer-by-layer assembly of poly-l-arginine (PLA) and iron-storage protein ferritin in a track-etched polycarbonate membrane (pore diameter: 400 nm) with subsequent dissolution of the template. The obtained (PLA/ferritin)₃ nanotubes (outer diameter: 410 ± 14 nm) were calcinated at 500 or 700 °C under air, yielding iron oxide nanotubes. After the calcination, the cylindrical hollow structure completely remained, but its diameter, wall thickness, and maximum length were significantly diminished. SEM measurements revealed that the nanotubes prepared at 500 °C consist of uniform hematite nanoparticles with ca. 5 nm diameter and the nanotubes calcinated at 700 °C are composed of ca. 20 nm hematite nanoparticles. These nanotubes showed efficient photocatalytic activity for degradation of 4-chlorophenol; higher catalytic activity was observed in the reaction with 5 nm hematite nanoparticle nanotubes.