The preparative conditions and stability of cis-[Co(NO2)4(NH3)2]-, which had been a missing link in the ammine-nitro cobalt(III) series until recently, were studied using 59Co NMR spectroscopy. The reaction of Na3[Co(NO2)6] with liquid ammonia mainly gave cis-[Co(NO2)4(NH3)2]- together with mer- and fac-[Co(NO2)3(NH3)3] and cis-[Co(NO2)2(NH3)4]+; the formation of trans-[Co(NO2)4(NH3)2]- was not observed. The reaction of aqueous [Co(NO2)6]3- with aqueous ammonia also gave the cis isomer as a major product. On the contrary, the cis isomer did not form during the conventional preparation from CoCl2 in an aqueous solution. The cis isomer was very stable in the solid state, but the isomer slowly isomerized in water (t1/2>5 days at room temperature, ca. 0.1mol dm-3) to the trans isomer. The reaction was accompanied by the formation of fac-[Co(NO2)3(NH3)3] which then isomerized to the mer isomer, and by the formation of several unknown species.
We have developed a novel multifunctional chromophore for photorefractive applications. This chromophore, a carbazole oligomer, possesses all the properties required for photorefractivity. Furthermore, because of its good film forming properties, it can be used for optical image processing. The photocarrier generation properties of this chromophore and its second-order nonlinear optical response in acceptor-substituted carbazoles were examined by xerographic discharge, second-harmonic generation, and electro-optic measurements. Photorefractivity was measured directly by two-beam coupling and four-wave mixing experiments.
In contrast to natural sequence of trypsin, functional sites of polar sequence of trypsin can be predicted only in the presence of cleavage site (CL) of the substrate, surface protein-F of viruses having strong or intermediate virulencies (Jellyfish model). In the case of less-virulent viruses, however, things are not so simple as virulent ones and sometimes DEV model fails to predict the functional sites which are already assinged empirically by virologists as the cleavage site just upstream to the long span of hydrophobic amino acids in the natural sequence. Actually, there are lots of weak virulent viruses in nature. Simple mathematical calculation supports this possibility which suggests a limitation in the application of our models. Mutation and selection are considered to control these situations (Appendix).
How information transfer occurs in trypsin in a water environment, is analyzed by the DEV model. Three possible trypsin structures, each being flexible, are involved, from which a dynamic cycle under biological regulation involving a trypsin substrate and surrounding water is proposed.
The contents of indole-3-acetic acid in the normal tissues and squamous cell carcinoma obtained from patients with esophageal cancer were determined by gas chromatography/high resolution-selected ion monitoring mass spectrometry. The contents of indole-3-acetic acid in cancer tissues were higher than those in neighboring normal tissues. The contents in normal tissues and squamous cell carcinoma are in the range of 90-390ng/g fw and in the range of 1400-4700ng/g fw, respectively. These data show that the production of indole-3-acetic acid was activated in the squamous cell carcinoma at the early differentiating stage. The increase of indole-3-acetic acid may concern the stimulation of the multiplication of esophageal cancer cells or the formation of such an inhibitor as indole-3-carbinol.