Two deformation paths in fission of light actinides

The correlation among the fission threshold energy, the scission configuration and the mass yield distribution has been studied in proton-induced fission of light actinides. It was found that there exist at least two fission paths from the threshold region to the scission. The elongated scission configuration is related with the fission process that goes over a higher threshold energy and results in a symmetric mass division mode, while the compact scission configuration with the process that experiences a lower threshold and ends up with an asymmetric mass division mode.     

Production and purification of organic reagents labeled with radioisotopes produced by an accelerator

We studied the production of nine typical organic analytical reagents labeled with¹¹C,¹³N and¹⁸F by irradiation with charged particles and bremsstrahlung and the purification of labeled compounds with HPLC and sublimation. As a result, we found that six reagents, α-naphthol, β-naphthol, quinoline, α-nitroso-β-naphthol, 8-hydroxyquinoline, and 1,10-phenanthroline H₂O could be labeled with¹¹C by bombarding a mixture of each reagent and boron with protons. More than 10% of the¹¹C was successfully exchanged with carbon atoms in the original reagents. We also found that sublimation is useful for purifying 8-hydroxyquinoline labeled with¹¹C. The extraction property of¹¹C-labeled 8-hydroxyquinoline between water and chloroform could be easily monitored by radioactivity measurement.     

Synthesis and properties of PI polyamide-SAHA conjugate

We have designed and synthesized new types of pyrrole (P)-imidazole (I) polyamide conjugates 1 and 2 possessing a suberoylanilide hydroxamic acid (SAHA) moiety that is a strong inhibitor of histone deacetylase (HDAC). SAHA conjugate 2 was designed to target the promoter region of the p16 tumor suppressor gene. The DNA binding affinity of SAHA conjugate 2 to its target sequence was examined using surface plasmon resonance. HDAC inhibition activity of conjugates 1 and 2 was evaluated using a colorimetric assay. The results demonstrated that even though it possesses the relatively large SAHA moiety, conjugate 2 has high DNA sequence-specific binding properties and moderate HDAC inhibitory activity in vitro. SAHA conjugate 2 was found to cause morphological changes in HeLa cells and to induce selective Histone H3 lysine 9 acetylation.     

Optimal control in a dissipative system: vibrational excitation of CO/Cu(100) by IR pulses

The question as to whether state-selective population of molecular vibrational levels by shaped infrared laser pulses is possible in a condensed phase environment is of central importance for such diverse fields as time-resolved spectroscopy, quantum computing, or "vibrationally mediated chemistry." This question is addressed here for a model system, representing carbon monoxide adsorbed on a Cu(100) surface. Three of the six vibrational modes are considered explicitly, namely, the CO stretch vibration, the CO-surface vibration, and a frustrated translation. Optimized infrared pulses for state-selective excitation of "bright" and "dark" vibrational levels are designed by optimal control theory in the framework of a Markovian open-system density matrix approach, with energy flow to substrate electrons and phonons, phase relaxation, and finite temperature accounted for. The pulses are analyzed by their Husimi "quasiprobability" distribution in time-energy space.     

Sugar-dependent aggregation of glycoconjugated chlorins and its effect on photocytotoxicity in HeLa cells

In order to explore the influence of the sugar moieties of glycoconjugated chlorins on the photocytotoxicity, we studied the photochemical properties of four glycoconjugated chlorins in aqueous media such as cytoplasm and the concentration dependence of photocytotoxicity in HeLa cells. In phosphate-buffered saline, the fluorescence intensities of 5,10,15,20-tetrakis[3-(beta-D-glucopyranosyloxy)phenyl]chlorin (m-1a) and 5,10,15,20-tetrakis[3-(beta-D-galactopyranosyloxy)phenyl]chlorin (m-1b), i.e., chlorins having hexose groups, were about 2-fold greater than those of 5,10,15,20-tetrakis[3-(beta-d-xylopyranosyloxy)phenyl]chlorin (m-1c) and 5,10,15,20-tetrakis[3-(beta-d-arabinopyranosyloxy)phenyl]chlorin (m-1d), i.e., chlorins having pentose groups, owing to a sugar-dependent difference of aggregation behavior. While no cytotoxicity was found in the dark, the highest photocytotoxicity was shown by m-1a (82% inhibition) in HeLa cells. This was higher than those of m-1b, m-1c, m-1d and tetraphenylporphyrin tetrasulfonic acid. The glycoconjugated chlorins except for m-1b appeared to be distributed diffusely throughout the cytoplasm. Among the four photosensitizers, m-1a showed the highest intensity in confocal fluorescence images, in agreement with the in vitro photocytotoxicity results. For m-1c, no photocytotoxicity was found at drug concentrations from 0.2 to 0.04 microM. Hence, sugar-dependent aggregation is not the major reason for the unexpected lack of efficacy of m-1c, which is uptaken efficiently by HeLa cells. For the glycoconjugated chlorins, these results suggest the biological aspects of sugar moiety play much crucial role rather than chemical aspects.     

Synthesis of the putative structure of fistulosin using the ruthenium-catalyzed cycloisomerization of diene

Fistulosin 1, which was isolated from the root of the Welsh onion, is a novel indole alkaloid that has antifungal activity. The first total synthesis of the reported structure of fistulosin using our cycloisomerization of diene is described.     

Formation of octacalcium phosphates with co-incorporated succinate and suberate ions

Octacalcium phosphates (OCPs) co-incorporated with various molar ratios of succinate and suberate ions were synthesized by wet processing. The interplanar spacings of the (100) planes (d(100)) of OCPs formed in the presence of succinic acid (Suc) or suberic acid (Sub) were larger than those of OCPs formed without addition of a dicarboxylic acid to the reaction solvent. The increases in the interplanar spacings of the (100) planes were caused by substitution of HPO(4)(2-) by dicarboxylate ions. The OCPs with co-incorporated succinate and suberate ions, i.e. solid solutions of OCP with incorporated Suc and Sub, were formed by reactions in the presence of Suc and Sub. When the Suc/(Suc + Sub) values in the starting compositions were in the range 0.45-1.0, Suc was preferentially incorporated into the OCP. In contrast, when the Sub/(Suc + Sub) values in the starting compositions were in the range 0.60-1.0, Sub was preferentially incorporated into the OCP crystals.     

Quantum transport phenomena in disordered electron systems with spin–orbit coupling in two dimensions and below

Electron transport phenomena in disordered electron systems with spin–orbit coupling in two dimensions and below are studied numerically. The scaling hypothesis is checked by analyzing the scaling of the quasi-1D localization length. A logarithmic increase of the mean conductance is also confirmed. These support the theoretical prediction that the two-dimensional metal in systems with spin–orbit coupling has a perfect conductivity. Transport through a Sierpinski carpet is also reported.