Radiation-induced reactions via the lowest excited states in cinnamic acid crystals

Radiation-induced reactions of cinnamic acid derivatives have been examined and compared with photoreactions in the crystalline state; all the reaction products were exactly the same as those of the photoreactions, indicating that the reactions proceed only via the lowest excited state to give [2 + 2] cycloadducts, E/Z isomerization products, or starting molecules.     

Surface properties of aqueous amino acid solutions. I. Surface tension of hydrochloric acid-glycine and glycine-sodium hydroxide systems

The surface tensions of aqueous solutions of four mixtures (hydrochloric acid-glycine hydrochloride, glycine hydrochloride-glycine, glycine-sodium glycinate, and sodium glycinate-sodium hydroxide) were measured as a function of total molality and mole fraction. The measurements correspond to the change in surface tension with variation of pH. The contribution of glycine hydrochloride to the increments in surface tension is equivalent to that observed for the aqueous solution of glycine, while the contribution of sodium glycinate is much larger than that of glycine. The variations in surface tension on mixing in the surface region are discussed using comparisons with mixtures of simple salts.     

An air-stable P-chiral phosphine ligand for highly enantioselective transition-metal-catalyzed reactions

A new P-chiral phosphine ligand, (R,R)-2,3-bis(tert-butylmethylphosphino)quinoxaline, has been prepared by the reaction of enantiomerically pure tert-butylmethylphosphine-borane with 2,3-dichloroquinoxaline. This ligand, in contrast to most of the previously reported P-chiral ligands, is an air-stable solid and exhibits excellent enantioselectivities in both Rh-catalyzed asymmetric hydrogenations and Rh- or Pd-catalyzed carbon-carbon bond-forming reactions.     

Stark beats of Lyman-α emission of foil-excited hydrogen atom

The Stark beats of Lyman-α emission due ton=1 ? 2 transition of hydrogen atom have been studied by the beam-foil method. After passage through a thin carbon foil, the static electric field of 500 V/cm was applied to the beam in the direction either parallel to or anti-parallel to the the beam velocity. The linearly polarized emission was measured by using a toroidal mirror at a Brewster's angle reflection. When the direction of the applied electric field is reversed, an appreciable phase shift was observed. The analysis of the data leads to the complete determination of the density matrix of the H(n=2) atoms at the time of their production.     

New design of a radio-frequency plasma torch

A numerical model has been developed for predicting the two-dimensional flow and temperature fields in a radio-frequency (rf) plasma torch. The method employed here is based on Boulos' model with the exception of the boundary conditions for the electric and magnetic field equations. Calculations have been made for the confirmation of a new sample injection method, which is capable of completely evaporating refractory materials at high feeding rates without interfering with the stability of the plasma. In the newly designed torch, the reagent is radially injected into the hottest part of the plasma through quartz capillary tubes set symmetrically between an inductor coil. Experimental investigations have also been performed for verifying the proper function of the design. These results provide evidence that our radial injection method developed here is more effective in practical processing than the conventional axial injection methods.     

Synthesis of Latia luciferin benzoate analogues and their bioluminescent activity

The bioluminescent system of the univalve shell Latia neritoides exhibits a luciferin-luciferase reaction. We study the enol formate structure of Latia luciferin, which is expected to be important for luminescent activity. The Latia luciferin analogues with an enol substituted benzoate moiety were synthesized and their bioluminescent activity was measured. The Latia luciferin benzoate analogues delay emission for natural luciferin in bioluminescence, indicating that the Latia bioluminescent activity can be controlled by the design of the enol ester.     

Oxidative addition and insertion reactions of cyclic alkyne-platinum(0) complexes

The reactions of various alkyne-platinum(0) complexes with methyl iodide and with iodine have been studied. The 3-hexyne complex Pt(C₂H₅C₂C₂H₅)(PPh₃)₂ gives alkyne-free oxidative addition products PtI(CH₃) (PPh₃)₂ and PtI₂ (PPh₃)₂ exclusively. In contrast, the strained cyclic alkyne complexes Pt(C₆H₈)(PPh₃)₂, Pt(C₇H₁₀)(PPh₃)₂, Pt(C₆H₈) (dppe) and Pt(C₇H₁₀) (dppe)¹ react with methyl iodide to give mainly 2-methylcycloalkenyiplatinum(II) complexes, e.g. PtI(C₆H₈CH₃) (PPh₃)₂, formed by electrophilic attack on the metal-alkyne bond. Iodine reacts similarly with Pt(C₆H₈) (PPh₃)₂ and Pt(C₇H₁₀) (PPh₃)₂ to give 2-iodocycloalkenylplatinum(II) complexes but, in the case of the corresponding dppe complexes, PtI₂(dppe) is the main product. The insertion reaction of methyl iodide with Pt(C₆H₈)(PPh₃)₂ proceeds via an oxidative addition intermediate PtI(CH₃) (C₆H₈) (PPh₃)₂ which can be isolated. Trifluoromethyl iodide reacts with Pt(C₆H₈)(PPh₃)₂ to give a 2-iodocyclohexenyl complex Pt(CF₃) (C₆H₈I) (PPh₃)₂ and with Pt(C₇H₁₀) (PPh₃)₂ to give PtI(CF₃) (PPh₃)₂. ³¹P NMR data are given and discussed.     

Flame-spread limit from interactive burning droplets in microgravity

This research conducted microgravity experiments on the flame spread over droplet-cloud elements with strong droplet interaction aboard Kibo on the ISS. The droplet-cloud element represents a local droplet pattern appearing in randomly distributed droplet clouds near the group-combustion-excitation limit and consists of small-droplet-spacing droplets and large-droplet-spacing droplets. As droplet-cloud elements, we used four n-decane droplets, Droplets C, B, A and L, placed at fiber intersections of two-dimensional SiC-fiber lattice with a 4-mm fiber interval in a combustion chamber. The flame spreads over the droplet-cloud element in order of Droplets C, B, A and L. The position of Droplet L relative to Droplet A was varied to investigate the flame-spread-limit distribution around burning Droplet A. The position of Droplet B relative to Droplet A was varied to investigate the effect of two-droplet interaction between Droplets B and A on the flame spread to Droplet L. The position of Droplet C relative to Droplet B was also varied to investigate the effect of three-droplet interaction among Droplets C, B and A. The results shows that in the case with the strong interaction by two or three interactive droplets, the high-temperature region is enlarged by the droplet interaction, centers near the center of mass of the interactive droplets and plays an important role in the flame-spread-limit distribution. Since the burning lifetime of Droplet A is finite, the flame-spread time from burning Droplet A to Droplet L is limited by burning lifetime of Droplet A and is less than 80% of the burning lifetime of Droplet A, which increases with the interactive effect. The flame-spread-limit distance from the center of mass of the interactive droplets increases with the burning lifetime.     

Spin-oriented projectile fragments: The first application tog-factor measurements

Ejectile nuclei in the fragmentation of intermediate-energy heavy-ion projectiles were found to be largely spin polarized. The observed polarization as a function of the outgoing momentum was nicely explained by a simple kinematical argument based on the participant-spectator model of projectile fragmentation. The measurements extended to cover several different targets, incident energies, exit channels, and emission angles revealed that substantial polarization shows up widely in projectile fragmentation reactions. Furthermore, this polarization exhibits an interesting behavior which may be interpreted as a manifestation of a gradual change in the deflection angle from positive to negative values as the energy increases and/or the target-Z decreases. The present polarization results also suggests various applications of spin polarized radioactive beams. As the first example of such an application, we present a recent result on theg-factor measurements on neutron-rich nuclei.