A newly developed diamond composite (Advanced Diamond Composite, ADC) was tested as the anvil material for a double-stage multianvil (MA6-8) apparatus. Pressures over 30GPa at room temperature were produced at relatively small press loads without any significant damages on the ADC anvils. The ADC anvil was found to be more transparent to X-ray beams of a wide range of energy as compared with a competitive sintered polycrystalline diamond (SYNDIE), and is accordingly suitable for an X-ray window under pressure. Electrical resistivity of ADC, however, is higher by about one order of magnitude than that of SYNDIE, which would restrict its use as a lead for electric power supply to the furnace. A hybrid anvil system with four ADC anvils plus four tungsten carbide anvils, the latter being used as the electric leads, was introduced for high temperature runs. This system has enabled to generate temperatures to 1500°C at pressures of 25-33GPa and to synthesize high-pressure phases relevant to the lower mantle mineralogy.
Diamond has been synthesized from cyclic hydrocarbons under high pressures between 6 to 9GPa and high temperatures ranging from 710 to 1290°C. The result offers a clue to the genesis of diamond in the deep interior of the earth.
The behavior of iron hydride was studied by in situ X-ray observations at 6GPa up to 700°C. When the iron-hydrogen system was heated, the dissolution of hydrogen into iron occurred, and bcc iron changed into iron hydride with a dhcp structure passing through a hcp structure, and then transformed into an fcc structure. The unit cell volumes per iron atom of these phases are much larger than those of bcc and hcp iron, which suggests that the iron hydride is formed. It was also found that the volume of the dhcp phase decreases with increasing temperature above 250°C, which indicates that the hydrogen concentration decreases at high temperatures.
The location of hydrogen-abstracted carbon atoms in alkane molecules has been found to depend strongly on the physical phase of the medium. In liquid branched alkanes at ambient temperature, hydrogen atoms preferentially abstract C-H hydrogen from the tertiary carbon atoms. In the amorphous solid of the branched alkanes at 77K, on the other hand, the hydrogen abstraction takes place very selectively at the penultimate secondary carbon atoms. In the crystalline solid of n-alkanes at 77K, hydrogen atoms abstract C-H hydrogen on penultimate or another internal secondary carbon atoms of the n-alkanes. In the amorphous solid of deuterated alcohols, the hydrogen abstraction takes place only at the penultimate carbon atoms of n-alkanes. These results indicate that the rate of chemical reaction in a condensed medium is determined not only by the steric factor and the activation energy of the reaction but also by the relaxation rate of the product molecule. A preliminary theory shows that the relaxation accelerates the reaction by enhancing transitions from an initial reactant state to many final states with different energies.
Successful delivery of genomic RNA of sweet clover necrotic mosaic virus to detached and intact leaf tissues of Vigna unguiculata cv. California Black Eye, has been demonstrated by using a simple biolistic device equipped with a polyacetal macroprojectile with RNA-coated gold particles, driven by gas pressure from a nitrogen cylinder controlled by a solenoid valve. The device is free of explosive heat and thus cell damage due to delivery operation is minimized.
The distribution of mollicutes in periwinkle plants (Catharanthus roseus (L.) G. Don) that had been graft-inoculated with the clover proliferation (CP) agent or the potato witches'-broom (PWB) agent was studied by in situ molecular hybridization with biotinylated single-stranded DNA probes and by DNA staining of hand sections of petioles and stem internode tissues with DAPI (4', 6-diamidino-2-phenylindole). In situ hybridization with the biotinylated probes was specific, detecting only the CP and PWB agents but not the western aster yellows (AY27) agent, which was detected by DAPI. The mollicutes were detected first in the external primary phloem tissue and then in the recently infected secondary phloem elements. Later, the spread of mollicutes was detected in the internal phloem tissue. In situ hybridization was highly specific and sensitive in detecting, without background signals, mollicutes in young sieve elements. However, the complete absence of hybridization signals and of DNA staining with DAPI coincided with degeneration of affected sieve tubes in the primary phloem elements.
Slice was prepared from the rat hippocampus and subjected to in situ hybridization of c-fos and other mRNAs after electrical recording of the neural activities. Anesthesia of the animal before dissection and supplementation of the medium with vitamins and amino acids improved the condition for mRNA expression. Low concentration of kainic acid induced both the epileptiform discharge and c-fos mRNA in CA3 pyramidal cells.