Two Triterpene Synthases from Imperata cylindrica Catalyzing the Formation of a Pair of Diastereoisomers through Boat or Chair Cyclization

Imperata cylindrica is known to produce a pair of triterpenes, isoarborinol and fernenol, that exhibit identical planar structures but possess opposite stereochemistry at six of the nine chiral centers. These differences arise from a boat or a chair cyclization of the B-ring of the substrate. Herein, we report the characterization of three OSC genes from I. cylindrica. IcOSC1 and IcOSC5 were identified as isoarborinol and fernenol synthases, respectively, while IcOSC3 was characterized as a multifunctional enzyme that produces glutinol and friedelin as its major products. Mutational studies of isoarborinol and fernenol synthases revealed that the residues surrounding the DCTAE motif partially affected the conformation of the B-ring during cyclization. Additionally, the IcOSC1-W255H mutant produced the rare triterpene boehmerol. The introduced histidine residue presumably abstracted a proton from the intermediary carbocation at C18 during the 1,2-rearrangement. Expression analysis indicated that all OSC genes were highly expressed in stems.     

The incorporation of low-substituted hydroxypropyl cellulose into solid dispersion systems

While the use of amorphous solid dispersions to improve aqueous solubility is well documented, little consideration has traditionally been given to the finished dosage form. The objective of this study was to evaluate the dissolution performance of amorphous solid dispersions containing a dispersed superdisintegrant with binding properties. KinetiSol® dispersing was used to thermally process hypromellose acetate succinate-based compositions containing the drug substance nifedipine (NIF) and a highly compressible grade of low-substituted hydroxypropyl cellulose (New Binder Disintegrants; NBD-grade). Solid-state analysis demonstrated that compositions were rendered amorphous during processing. Tablets containing intra-dispersion NBD were found to exhibit non-sink dissolution performance similar to milled intermediate, demonstrating excellent disintegration characteristics. Conversely, tablets without intra-dispersion NBD were found to release significantly less NIF during dissolution analysis due to particle agglomeration. It was determined that compressibility and particle wetting increased as the level of intra-dispersion NBD increased.     

Restraint Method for Overcoming Heating Irregularity and Improving Heating Equipment Efficiency for Beverage Cans Using High‐Frequency Induction Heating

We were able to reduce heating irregularities in equipment for heating beverage cans by using the high‐frequency induction heating method and determining the resulting improvement in the heating efficiency. The heating irregularity between the top and bottom of the can was reduced to less than 3°C by improving the arrangement of the heating coils for the beverage can by thinning the winding and changing the circuit configuration. The efficiency of power conversion was improved from 93.0% to 97.4%. In this paper, the configuration of the equipment and the experimental results are reported.     

Fretting fatigue in hydrogen gas

To clarify the effect of hydrogen gas on fretting fatigue strength of the materials, which supposed to be used for hydrogen utilization machines, fretting fatigue tests were conducted in hydrogen gas. It is important to take fretting fatigue into account in strength design, because many fatigue failure accidents have occurred at joints or contact parts between components. As a part of the experiments, an austenitic stainless steel was focused in this paper. The material was SUS 304. Fretting fatigue strength in hydrogen gas decreased compared with that in air. Tangential force coefficient increased in the reverse order of fretting fatigue strength. Therefore, one of the reasons of the decrease of fretting fatigue strength was that tangential force was different depending on the environment. Absorption of hydrogen occurred during fretting in hydrogen gas was detected. The absorption could be considered as one of the causes of the decrease of fretting fatigue strength, since fretting fatigue life of pre-charged specimen was decreased and also the crack propagation threshold of short fatigue crack was reduced by hydrogen charge.     

Long‐Lived Flexible Displays Employing Efficient and Stable Inverted Organic Light‐Emitting Diodes

Although organic light‐emitting diodes (OLEDs) are promising for use in applications such as in flexible displays, reports of long‐lived flexible OLED‐based devices are limited due to the poor environmental stability of OLEDs. Flexible substrates such as plastic allow ambient oxygen and moisture to permeate into devices, which degrades the alkali metals used for the electron‐injection layer in conventional OLEDs (cOLEDs). Here, the fabrication of a long‐lived flexible display is reported using efficient and stable inverted OLEDs (iOLEDs), in which electrons can be effectively injected without the use of alkali metals. The flexible display employing iOLEDs can emit light for over 1 year with simplified encapsulation, whereas a flexible display employing cOLEDs exhibits almost no luminescence after only 21 d with the same encapsulation. These results demonstrate the great potential of iOLEDs to replace cOLEDs employing alkali metals for use in a wide variety of flexible organic optoelectronic devices.     

Effect of water on vapor phase photografting on cellulose and its derivatives

Effect of water on vapor phase photografting on cellulose was investigated at 60°C. An activated grafting of methyl methacrylate by water contained in the sample was observed in the experiment. The effect of water was commonly recorded irrespective of the type of cellulose derivatives such as cellulose acetate (degree of substitution, DS = 0.18 and 0.33), cellulose nitrate (DS = 0.35 and 0.75), and carboxymethl cellulose (DS = 0.19 and 0.74). Organic solvents can also be used in place of water, indicating that the percent grafting decreases in the order, water > methanol > acetone > cyclohexane. From ESR studies, water in the sample was found to contribute to the decay of cellulose radicals rather than to the radical formation. The decay was accelerated by organic solvents, and the magnitude of the effect was in the order, water ≈ methanol > acetone > cyclohexane. Based on the above investigation, it was presumed that water contained in the sample cannot contribute directly to the formation of cellulose radicals which may initiate grafting, but mostly promotes the penetration of monomer into cellulose fibers. Such penetration could lead cellulose radicals to an effective initiation of grafting.     

Simulations on various lubrication boundaries between diamond-like carbon films

Molecular dynamics (MD) simulations were used to study a sliding friction process between DLC films on various boundary conditions. The experimental results revealed that, in the absence of a lubricant, a transfer film between the DLC films was formed. In contrast, when the oil or water lubricants were added to lubricate between the DLC films, a boundary lubrication layer was found. The friction forces on the water and oil lubrication were almost the same, but the friction force in the absence of a lubricant was larger than those on the water and oil lubrication. The conclusions were in good agreement with the experiments.     

Ethynylene-disilanylene copolymers

Polymers of structure (SiR₂SiR₂-C C-SiR₂SiR₂-C C) _n , in which ethynylene units alternate with disilylene units, have been prepared by two routes: (a) condensation of dichlorodisilanes with dilithium derivatives of 1,2-diethynyldisilanes and (b) ring-opening polymerization of strained cyclic disilanylene-acetylnes, (SiR₂SiR₂C C)₂. The polymers display UV absorption near 240 nm indicative of – conjugation between the Si₂ and the C C moieties. Polymers with R=R=n-Bu or R=n-Bu, R=Ph, undergo solid-state transitions to form liquid crystalline mesophases resembling those observed for many poly(silylenes). Single crystals were obtained for the polymer with R=R=CH₃, by precipitation from dilute cyclohexane solution. The solid-state properties and structures of this family of polymers are discussed.This paper was presented at the Second International Topical Workshop, Advances in Silicon-Based Polymer Science.     

Temperature dependent electrical conductivity of p-doped poly(3,4-ethylenedioxythiophene) and poly(3-alkylthiophene)s

Summary Temperature dependent electrical conductivity of substituted polythiophenes (poly(3,4-ethylenedioxythiophene) PEDOTh and head-to-tail type poly(3-alkylthiophene) HT-P3RTh) has been measured. The electrical conductivity (σ) of p-doped PEDOTh and HT-P3RTh obeys equations of a type, ln σ= ln σ_o− (T_o/T)^0.25, with the T_o value of about 10⁵–10⁷ K. Received: 21 December 1998/Revised version: 8 February 1999/Accepted: 15 February 1999     

Effects of cyclic vertical loading on bearing and pullout capacities of piles with continuous helix wing

Laboratory and field tests were conducted to investigate the bearing and pullout capacities of steel piles with a continuous helix wing during cyclic loading. Both continuous helix and straight-sided piles were subjected to monotonic compressive, monotonic tensile, and cyclic reversal loading in the laboratory, while only the continuous helix pile was tested in the field. Both the laboratory and the field tests showed that the bearing and pullout capacities of the continuous helix pile under cyclic reversal loading decreased to approximately 60–80% of those of the pile under monotonic loading, with a larger reduction seen in the laboratory tests. The decrease in resistance was mainly due to the reduction in shaft friction, which was likely to be the result of soil disturbance and loosening around the pile with cyclic loading. The laboratory tests also showed that the tip resistance of the straight-sided pile under cyclic reversal loading was reduced, similarly due to the loosening of the soil, particularly underneath the pile tip. The tip resistance of the continuous helix pile, in contrast, did not degrade with cyclic loading, owing to the presence of the wing immediately above the pile tip that inhibited the loosening of the soil. These findings were supported by similar field test observations.