Enantioselective Total Synthesis of Dysidavarone A,a Novel Sesquiterpenoid Quinone from the Marine Sponge Dysidea avara

Dysidavarone A, a structurally unprecedented sesquiterpenoid quinone, was synthesized in 30 % overall yield in a longest liner sequence of 13 steps from commercially available o‐vanillin. A highly strained and bridged eight‐membered carbocyclic core was established by the C7?C21 carbon bond formation through a copper enolate mediated Michael addition to the internal quinone ring.     

End effects for a rodlike polyelectrolyte molecule in salt solution

Electrostatic potentials around a single rodlike polyelectrolyte molecule are calculated by solving the nonlinear Poisson–Boltzmann equation numerically in the presence of externally added salt. The polyion is regarded as a cylinder with a finite length whose side surface is uniformly charged and end surfaces uncharged. The calculations show that the distance to which end effects extend is about half the Debye screening length and is almost independent of the surface charge density and concentration of added salt. For a long polyion whose length is much greater than the Debye length, the end effects can be neglected even for a polyelectrolyte with high surface charges, whereas they play an important role for a short polyion with a length of the same order as the Debye length. In addition, a strong charge condensation is found in the direction of the axis of the cylinder for a long polyion.     

Electronic properties of CrF and CrCl in the X 6Sigma+ state: observation of the halogen hyperfine structure by Fourier transform microwave spectroscopy

The rotational spectra of the CrF and CrCl radicals in the X 6Sigma+ state were observed by employing a Fourier transform microwave spectrometer. The CrF and CrCl radicals were generated by the reaction of laser-ablated Cr with F2 and Cl2, respectively, diluted in Ar. A chromium rod made of chromium powder pasted with epoxy resin was ablated by a Nd:YAG laser. Rotational transitions were measured in the region between 8 and 26 GHz. Several hyperfine constants due to the halogen nuclei were determined by a least-squares analysis. The electronic properties of CrF and CrCl were derived from their hyperfine constants and were compared with those of other 3d transition metal monohalides: TiF, MnF, FeF, CoF, NiF, and FeCl.     

Synthesis and antitumor evaluation of some 1,3-disubstituted tetrahydropyrimido[4,5-c]isoquinolines

Cyclocondensation of 6-amino-2,4-dioxopyrimidine or 2,4,6-triaminopyrimidine with 1-cyclohexenecarbox-aldehyde 13 afforded regiospecifically, tricyclic, angular 1,3-disubstituted tetrahydropyrimido[4,5-c]isoquin-olines 5 and 6 respectively. In addition, 2,4,6-triaminopyrimidine when condensed with 2-chloro-1-cyclohex-enecarboxaldehyde 14 , regiospecifically afforded the angular isomer 6 . However, the cyclocondensation of 2,6-diamino-4-oxopyrimidine with 13 was regioselective and afforded a mixture of the linear and angular tetrahydropyrimidoisoquinolines 2 and 4 . The growth of leukemia L-1210 cells in culture were inhibited 50% by 6 at 9 × 10^?8 M. Compounds 4 and 5 were not significantly active.     

An Accurate Characterization of CRT Monitor (I) Verifications of Past Studies and Clarifications of Gamma

CRT monitors are widely used to view images on the Internet. The color images on the computer graphic display can be printed out or displayed on other monitors through the Internet, and color matching between the original and the reproduction is very important. The color management systems (CMSs) are useful for the color matching. CMSs utilize device profiles, in which color characteristic information is stored, and these profiles are generated by device characterization. Thus, an accurate characterization of the monitor is essential for better color matching. CRT monitor characteristics can be described by the tone reproduction curves (TRCs) of each channel, and color additive matrix. In this paper, these characteristics were investigated from a physical point of view. Various kinds of flare and the interdependence among the channels were also investigated and verified. The definition of the term “gamma” is clarified, which is very often used to describe the TRC. Various definitions are compared and a new definition of S-γ is proposed.