Crystal structure of two lipophilic antifolates: 2,4-diamino-5-(n-hexyl)-6-methylpyrimidine and 2,4-diamino-5-(n-heptyl)-6-methylpyrimidine ethanesulfonate

The 5-hexyl (I) and the 5-heptyl (II) analogs of 2,4-diamino-6-methylpyrimidine both crystallize in the space groupP2₁/c withZ=4. Unit cell parameters of I are C₁₁H₂₀N₄·H₂O,a=17.204(3),b=4.609(9),c=16.765(2)Å,= 91.53(2)°; those of II are C₁₂H₂₃N₄ ⁺·C₂H₅SO₃ ^–,a=12.489(1),b=16.702(2),c=8.9558(7)Å,=99.208(8)°. The molecular packing of I contains one water, while II forms a salt with ethanesulfonic acid. The alkyl chain of I adopts an alltrans conformation; in contrast, II has onegauche orientation between carbons 2 and 3 of heptyl. These are the first structural data on two alkyl lipophilic antifolates with antineoplastic activity.     

Development of a Compact Tritium Gas Recycling System

JAERI has been developing an improved compact tritium gas enrichment/recycling system for efficient research and development work using tritium. A proton conductor has been investigated and a compact enrichment system was designed with a hydrogen pump employing a proton conductor. The pump can separate hydrogen directly from the helium gas carrier and minimize the size of the system. A prototype hydrogen pump was developed and its performance test was started. This revised version was published online in August 2006 with corrections to the Cover Date.     

Yamadazyma Farinosa IFO 10896-Mediated Reduction of 4,4-Dimethoxy-2-Butanone as the Key-Step for the Preparation of 1,3-Diols with Unsymmetrical Substituents

(R)-4,4-Dimethoxy-2-butanol was prepared with the action of Yamadazyma farinosa IFO 10896 on 4,4-dimethoxy-2-butanone, and subsequently converted to (2R,4R)- and (2R,4S)-isomers of 6-hepten-2,4-diol by the treatment with allyl bromide and indium in aqueous solution.     

Determination of the presence or absence of sulfur materials in drywall using direct analysis in real time in conjunction with an accurate-mass time-of-flight mass spectrometer

Based on the concern about the presence of sulfur materials being in drywall (wallboard), a quick and reliable test to confirm the presence or absence of these materials using direct analysis in real time (DART) mass spectrometry in conjunction with an accurate-mass time-of-flight (TOF) mass spectrometer has been developed and is described here.     

Radiation defects in nano-structured materials

We investigated defect formation within nanostructured materials using a transmission electron microscope (TEM) and ion accelerators. Controlling diffusion coefficient of the defects we have first observed changes in pattern of defect clusters, namely, the diffusion-limited reaction of defects in nanocrystals. Received 30 November 2000     

Controllable growth and characterization of isolated single-walled carbon nanotubes catalyzed by Co particles

Discrete Co catalytic nanoparticles with small diameters are obtained by pulsed vacuum arc evaporation on Si/SiO₂ substrates, which are used for the growth of isolated single-walled carbon nanotubes (SWNTs) by an ethanol chemical vapor deposition approach (CVD). The distributions of catalytic nanoparticles change with the number of arc pulses, which allows control of the nanotubes formation. We find that an increase of ethanol pressure during CVD growth can change SWNTs from isolated ones into bundles. A new growth mechanism which combines a tip and base model for SWNT growth has been tentatively proposed. It is suggested that the small size catalytic particles prepared by pulsed arc evaporation have a potential advantage for small diameter SWNT growth. PACS 78.67.Ch; 78.67.Bf; 78.67.-n; 81.07.De; 61.46.-w