Allelopathic Effects of Volatile Monoterpenoids Produced by <Emphasis Type="Italic">Salvia leucophylla</Emphasis>: Inhibition of Cell Proliferation and DNA Synthesis in the Root Apical Meristem of <Emphasis Type="Italic">Brassica campestris</Emphasis> Seedlings

Salvia leucophylla, a shrub observed in coastal south California, produces several volatile monoterpenoids (camphor, 1,8-cineole, -pinene, -pinene, and camphene) that potentially act as allelochemicals. The effects of these were examined using Brassica campestris as the test plant. Camphor, 1,8-cineole, and -pinene inhibited germination of B. campestris seeds at high concentrations, whereas -pinene and camphene did not. Root growth was inhibited by all five monoterpenoids in a dose-dependent manner, but hypocotyl growth was largely unaffected. The monoterpenoids did not alter the sizes of matured cells in either hypocotyls or roots, indicating that cell expansion is relatively insensitive to these compounds. They did not decrease the mitotic index in the shoot apical region, but specifically lowered mitotic index in the root apical meristem. Moreover, morphological and biochemical analyses on the incorporation of 5-bromo-2-deoxyuridine into DNA demonstrated that the monoterpenoids inhibit both cell-nuclear and organelle DNA synthesis in the root apical meristem. These results suggest that the monoterpenoids produced by S. leucophylla could interfere with the growth of other plants in its vicinity through inhibition of cell proliferation in the root apical meristem.     

Intrinsic Elastic, Dielectric, and Piezoelectric Losses in Lead Zirconate Titanate Ceramics Determined by an Immittance-Fitting Method

The material coefficients of "soft" and "hard" lead zirconate titanate (PZT) ceramics were determined as complex values by the nonlinear least-squares-fitting of immittance data measured for length-extensional bar resonators. The piezoelectric d -constant should be a complex value to obtain a best fitting between observed and calculated results. Because the elastic, dielectric, and piezoelectric losses determined in this process were not "intrinsic" losses, a calculation process to evaluate the "intrinsic" losses was proposed. It was confirmed that the intrinsic losses were smaller than the corresponding extrinsic losses. The intrinsic piezoelectric loss existed in both soft and hard PZTs; ∼50% of the loss of piezoelectric d -constant was derived from the elastic and dielectric losses. The most notable difference between the soft and hard PZTs was observed in their elastic losses.     

New multicolor and rewritable holographic polymer film for three‐dimensional holographic display

We have developed a new multicolor holographic polymer film. Our holographic polymer film contains 3‐[(2,4,6‐trichloro)azo]‐9H‐carbazole‐9‐ethanol (A‐1) and poly(methyl methacrylate). The holographic polymer film can be recorded with a holographic image without applying an external electric field. The diffraction efficiency was 57% at A‐1 with a 20 wt% of dope ratio. The writable holographic image writing for the holographic polymer film step used the silver halide photographic emulsion master plate 532‐nm laser beam under the nonelectric field. After the copy hologram is formed, our holographic polymer film can be displayed in red and green holographic images. Even though our holographic polymer film is rewritten over 200 times, the diffraction efficiency does not fall. As the holographic polymer film is manufactured using roll‐to‐roll techniques, although still in a laboratory scale in this study, it has a strong possibility of being manufactured in larger sizes with lower cost.     

A negative resist for KrF excimer laser lithography

The design and preparation of a series of negative resists for KrF excimer laser lithography are described. Each resist is composed of poly(hydroxystyrene) and an aromatic azide. The base resin shows high transmittance of 62%/μm at 248 nm, when p-ethylphenyl p-azidophenylsulfonate. 4-azido-4α-methoxy-chalcone, 1-(4 azidobenzylidene)-3-(α-hydroxy-4-azidobenzyl)-indene, 4,4α-diazido-3,3α-dimethoxybiphenyl, or 1-(4-azidostyryl)-5, 5-dimethyl-2-cyclohexen-1-one is employed as a sensitizer. These azides are obtained by red-shifting the absorption maxima to lower energy regions than the exposing wavelength of 248 nm. Transmittance of resists can be controlled from 10 to 30%. The resist is exposed with a KrF excimer laser stepper and developed in an alkaline solution. Sensitivities of about 15 mJ/cm² are observed. A good, subhalf-micron resist profile is achieved. The photochemical reaction mechanisms of poly(hydroxystyrene) and 4,4α-diazido-3,3α-dimethoxybiphenyl were studied at 248 nm and 313 nm exposure. Quantum yield for photodecomposition at 248 nm is seven times larger than that at 313 nm, but dissolution-inhibition effects are larger at 313 nm exposure. Consequently, the resist shows higher sensitivity at 313 nm than at 248 nm.     

The effect of sputter etching on the surface characteristics of dyed aramid fabrics

Three kinds of aramid fabrics, Technora (modified p-aramid), Conex (m-aramid) and Kevlar (p-aramid), were subjected to sputter etching and argon low-temperature plasma treatments after dyeing in black with disperse dyes. The depth of shade increased considerably on Technora and Kevlar with the sputter etching treatment, but not on Conex fabrics. Argon low-temperature plasma treatment had virtually no effect on the depth of shade on the aramid fabrics.     

Preparation of Aluminum Nitride Powder from Aluminum Polynuclear Complexes

AIN powder was synthesized from aluminum polynuclear complexes. Basic aluminum chloride and basic aluminum lactate were used as the aluminum polynuclear complexes. These starting materials and glucose were dissolved in water and mixed homogeneously. AIN powder was obtained by calcining after drying and precalcining at 800°C under nitrogen gas flow. Then excess carbon was removed by firing in air. Nitridation in the system was investigated and compared with that in the alumina–carbon black system. It was found that in our reaction system nitridation began and proceeded at lower calcination temperatures above 1200°C than in the alumina–carbon black system. Using aluminum polynuclear complexes, AIN was synthesized through the nitridation of γ-alumina and produced in a very fine and sharp particle size distribution.     

Oxygen evolution anodes composed of anodically deposited Mn-Mo-Fe oxides for seawater electrolysis

Preparation of anodes for oxygen evolution in seawater electrolysis was carried out. Manganese-molybdenum double oxides, Mn_1−xMo_xO_2+x, prepared by anodic deposition from MnSO₄-Na₂MoO₄ solutions showed the 100% oxygen evolution efficiency at a current density of 1000 A m⁻² in 0.5 M NaCl at 30 °C and pH 12, but an increase in solution temperature resulted in dissolution of the oxides as molybdate and permanganate ions. In order to increase the stability of the electrodes at higher temperatures the addition of iron to the manganese-molybdenum oxides was performed by anodic deposition in MnSO₄-Na₂MoO₄-FeNH₄(SO₄)₂ solutions. The electrodes thus prepared showed the 100% oxygen evolution efficiency at 1000 A m⁻² in 0.5 M NaCl at 30-90 °C, when proper amounts of molybdenum and iron were contained. The iron addition also enhanced the oxygen evolution efficiency. The electrodes were not composed of oxide mixtures but triple oxides, Mn_1−x−yMo_xFe_yO_2+x−0.5y, consisting of Mn⁴⁺, Mo⁶⁺ and Fe³⁺. The formation of the triple oxides seemed responsible for enhancement of both oxygen evolution efficiency and stability.     

Free primary alcohols in oils and waxes from germs,kernels and other components of nuts,seeds, fruits and cereals

The composition of free primary alcohols in oils and waxes obtained from the germ, kernel, seed coat, shell and skin (peel) of various nuts, seeds, fruits and cereals and from the chrysalis of silkworm was examined. These alcohols are usually present in small amounts, along with large quantities of hydrocarbons, esters and glycerides in oils and waxes. Thus, it is necessary to remove hydrocarbons, esters and glycerides to analyze the alcohols. We found that preparative reverse-phase thin-layer chromatography (TLC) was the best way to isolate alcohols from oils and waxes. Gas liquid chromatography (GLC) then detected hexacosanol, octacosanol and triacontanol in the oils and waxes. Octacosanol usually was the predominant alcohol. Relationships between the organs from nuts, seeds, fruits and cereals and the contents of octacosanol are suggested. For example, degermed kernels contained two times more octacosanol than the germ, and the skin coat and shell contained one-half and one-fortieth the octacosanol of the germ, respectively.     

Microstructure and Thermal Shock Resistance of Molten Glass-Coated Carbon Materials Fabricated by Interfacial Control

Carbon substrates were coated completely with a molten silicate glass, where the wettability of carbon to glass was improved by infiltration and pyrolysis of perhydropolysilazane. Microstructures of the carbon–glass interface were dependent on P n ₂ during coating. Coating at lower P n ₂ induced the formation of cristobalite at the carbon–glass interface. When the coating was performed at higher P n ₂, the glass and carbon were strongly adhered, without the formation of cristobalite. Coating at higher P n ₂ improved the thermal shock resistance of the glass layer, because crack initiation was not induced by the phase transformation of cristobalite during the cooling process. In the case of coating at higher P n ₂, an oxynitride glass layer was formed at the glass subsurface by dissolution of N₂. A porous glass subsurface layer with uniform spherical micro-pores could be produced by soaking near the glass transition temperature in a steam environment. The porous layer with fine and homogeneous microstructure acts as a thermal shock absorbing layer, so that glass-coated carbon with a porous glass layer has excellent thermal shock resistance in addition to steam oxidation resistance.     

Fabrication and Microstructure Characterization of Ti3SiC2 Synthesized from Ti/Si/2TiC Powders Using the Pulse Discharge Sintering (PDS) Technique

Ti/Si/2TiC powders were prepared using a mixture method (M) and a mechanical alloying (MA) method to fabricate Ti₃SiC₂ at 1200°–1400°C using a pulse discharge sintering (PDS) technique. The results showed that the Ti₃SiC₂ samples with <5 wt% TiC could be rapidly synthesized from the M powders; however, the TiC content was always >18 wt% in the MA samples. Further sintering of the M powder showed that the purity of Ti₃SiC₂ could be improved to >97 wt% at 1250°–1300°C, which is ∼200°–300°C lower than that of sintered Ti/Si/C and Ti/SiC/C powders using the hot isostatic pressing (HIPing) technique. The microstructure of Ti₃SiC₂ also could be controlled using three types of powders, i.e., fine, coarse, or duplex-grained, within the sintering temperature range. In comparison with Ti/Si/C and Ti/SiC/C mixture powders, it has been suggested that high-purity Ti₃SiC₂ could be rapidly synthesized by sintering the Ti/Si/TiC powder mixture at relatively lower temperature using the PDS technique.