Synthesis of poly(2,6-dimethyl-1,4-phenylene oxide) derivatives in water using water-soluble copper complex catalyst with natural ligands

Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) was synthesized by oxidative polymerization of 2,6-dimethylphenol (DMP) using a water-soluble copper complex catalyst under oxygen and with natural ligands in alkaline water. Arginine, guanine, adenine, cytosine, histidine, and folic acid were used as ligands for the copper complex. Arginine performed the best, with a yield of 72%, a number-average molecular weight (M_n) of 4400, and a molecular weight distribution (M_w/M_n) of 1.7. It was then used to optimize reaction conditions. Surfactants, temperature, and sodium hydroxide concentration were varied in copolymerization of DMP and 2-allyl-6-methylphenol (AMP) to produce allyl-containing PPO with 77% yield (M_n = 4500; M_w/M_n = 1.8). The optimum conditions were applied to copolymerization of DMP, AMP, and bisphenol A, leading to dihydroxyl PPO analogs containing thermally cross-linkable allyl groups. The thermal properties of these thermosetting PPOs were studied by differential scanning calorimetry, thermogravimetric analysis, and Fourier-transform infrared spectroscopy.     

2,2′‐(Methylimino)bis(N,N‐dioctylacetamide) (MIDOA), A New Tridentate Extractant for Technetium(VII), Rhenium(VII), Palladium(II), and Plutonium(IV)

2,2′‐(Methylimino)bis(N,N‐dioctylacetamide) (MIDOA) was developed as a new extractant for technetium. MIDOA has a similar backbone to TODGA, N,N,N′,N′‐tetraoctyldiglycolamide, where the nitrogen atom bearing a methyl group replaces the ether oxygen in TODGA. MIDOA is highly lipophilic and ready to use in the HNO₃–n‐dodecane extraction system. The distribution ratio (D) for Tc(VII) is extremely high. In addition, Cr(VI), Re(VII), Mo(VI), W(VI), Pd(II), and Pu(IV) are well extracted by MIDOA. MIDOA has high selectivity toward certain oxometallates. The D(Tc) values decrease gradually with HNO₃, H⁺, and NO₃ ^? concentrations, and the log D vs log [MIDOA] dependence indicates the species extracted to be the 1:1 metal‐ligand complex. It is clear that MIDDA [2,2′‐(methylimino)bis(N,N‐didodecylacetamide)] and IDDA [2,2′‐(imino)bis(N,N‐didodecylacetamide)], which have structures analogous to MIDOA, have similar extraction behavior to that of MIDOA.     

Preparation of zinc oxide ceramics with a sustainable antibacterial activity under dark conditions

Fabrication of ZnO ceramics with a sustainable antibacterial activity even in the dark has been conducted. Fine ZnO powders were hydrothermally treated in 0.5–3 mol ml^?1 Zn(NO₃)₂ aqueous solutions at 110–180 °C for 3–20 h. After an uniaxial pressing of the ZnO powders thus prepared, they were sintered at 400–600 °C for 1 h in air. Sustainability in antibacterial activity was evaluated using a colony count method with Escherichia coli bacteria on nutrient agar medium (36 °C/24 h) in a Na–P-buffer solution. The best data was attained for the ZnO ceramics prepared from the following conditions: a 3 mol ml^?1 zinc nitrate solution for the hydrothermal treatment at 120 °C for 7 h and sintering in air with a step-by-step pattern (470 °C/1 h–485 °C/1 h–500 °C/1 h). ESR and chemical photoluminescence analyses have cleared that radical oxygen of super-oxide (O₂^?) originated from the surface of ZnO might exhibit an antibacterial activity even under the dark condition.     

Isolation of a CDC25 family gene,MSI2/LTE1, as a multicopy suppressor of ira1

We have identified MS12 as a gene of Saccharomyces cerevisiae which, when on a multicopy vector, suppresses the heat shock sensitivity caused by the loss of the IRA1 product, a negative regulator of the RAS protein. The multicopy MSI2 also suppresses the heat shock sensitivity of cells with the RAS2^val19 mutation but not those with the bcy1 mutation, suggesting that the MSI2 protein may interfere with the activity of the RAS protein. The sequence analysis of MSI2 reveals that it is identical to LTE1 belonging to the CDC25 family: CDC25, SCD25 and BUD5, each of which encodes a guanine nucleotide exchange factor for the ras superfamily gene products. Deletion of the entire MSI2 coding region reveals that MSI2 is not essential but the disruptant shows a cold-sensitive phenotype. Under the non-permissive conditions, more than 70% of the msi2 disruptants arrested at telophase as large budded cells with two nuclei divided completely and elongated spindles, indicating that the msi2 deletion is a cell division cycle mutation. These results suggest that MSI2 is involved in the termination of M phase and that this process is regulated by a ras superfamily gene product.     

Synthesis and properties of destructible anionic and cationic surfactants with a 1,3-dioxolane ring

A convenient synthetic method for the preparation of destructible surfactants containing a 1,3-dioxolane ring with various substituents is described. The substituents include carboxylate, quaternary ammonium, and several aliphatic alkyl groups, such as hydrophilic or hydrophobic groups. These novel surfactants had good surface activity, and were easily hydrolyzed under acidic conditions. They also catalyzed aliphatic halide substitution.     

Perception of complex geometric figures in chimpanzees (Pan troglodytes) and humans (Homo sapiens): Analyses of visual similarity on the basis of choice reaction time.

In a conditional-discrimination task (matching-to-sample), assessed similarities among figures consisting of 2 elemental figures through the choice reaction time (RT), nonmetric multidimensional scaling, and hierarchical cluster analysis of data from chimpanzees (Pan troglodytes) and humans (Homo sapiens). Humans also rated similarities among figures. The results of the 3 experiments clearly indicated that the RT data obtained from chimpanzees' performances were useful measures of the similarities among figures. The results suggested that chimpanzees and humans perceived the complex figures similarly. The outer-contour elements were perceived most dominantly by both species, and the straight-line elements were perceived least dominantly. Both species showed the same perceptual hierarchy or dominance among perceptual categories, as determined by the similarity of simple elements, on the basis of transformational invariances. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temperature-dependence mechanism of tensile strength of Si-Ti-C-0 Fiber-Aluminum matrix composites

The mechanism for the temperature dependence of the tensile strength of unidirectional hybrid type Si-Ti-C-O (Tyranno) fiber-reinforced aluminum matrix composite, in which SiC-particles are dispersed in the matrix, is discussed, focusing on the temperature dependencies of the stress concentration arising from broken fibers and critical length and their influences on the composite strength, by means of a shear-lag analysis and a Monte Carlo simulation. The main results are summarized as follows. The softening of the matrix at high temperatures raises the composite strength from the point of decrease in stress concentration, but on the other hand, it also reduces strength from the point of increase in critical length, which reduces the stress-carrying capacity of broken fibers over a long distance. The reason why the measured strength of composite decreased with increasing temperature could be attributed to the predominacy of the latter effect over the former one. The results of the simulation indicated that the hybridization of the composites improved room-temperature and high-temperature strengths through the strengthening of the matrix.     

Ozone fading of phenolphthalein and aurin

The reactions of phenolphthalein, which exists as a lactone-quinonoid tautomeric mixture in solution, and aurin with ozone have been examined. The reactivity of the lactone tautomer of phenolphthalein with ozone was found to be low and the ozone attacks the aromatic ring. In the case of the quinonoid tautomer the ozone readily reacts with the carbon skeleton. In the case of aurin ozone also attacks the carbon skeleton.     

Expression of endothelin-1 in the lungs of patients with pulmonary hypertension

BACKGROUND: Pulmonary hypertension is characterized by an increase in vascular tone or an abnormal proliferation of muscle cells in the walls of small pulmonary arteries. Endothelin-1 is a potent endothelium-derived vasoconstrictor peptide with important mitogenic properties. It has therefore been suggested that endothelin-1 may contribute to increases in pulmonary arterial tone or smooth-muscle proliferation in patients with pulmonary hypertension. We studied the sites and magnitude of endothelin-1 production in the lungs of patients with various causes of pulmonary hypertension. METHODS: We studied the distribution of endothelin-1-like immunoreactivity (by immunocytochemical analysis) and endothelin-1 messenger RNA (by in situ hybridization) in lung specimens from 15 control subjects, 11 patients with plexogenic pulmonary arteriopathy (grades 4 through 6), and 17 patients with secondary pulmonary hypertension and pulmonary arteriopathy of grades 1 through 3. RESULTS: In the controls, endothelin-1-like immunoreactivity was rarely seen in vascular endothelial cells. In the patients with pulmonary hypertension, endothelin-1-like immunoreactivity was abundant, predominantly in endothelial cells of pulmonary arteries with medial thickening and intimal fibrosis. Likewise, endothelin-1 messenger RNA was increased in the patients with pulmonary hypertension and was expressed primarily at sites of endothelin-1-like immunoreactivity. There was a strong correlation between the intensity of endothelin-1-like immunoreactivity and pulmonary vascular resistance in the patients with plexogenic pulmonary arteriopathy, but not in those with secondary pulmonary hypertension. CONCLUSIONS: Pulmonary hypertension is associated with the increased expression of endothelin-1 in vascular endothelial cells, suggesting that the local production of endothelin-1 may contribute to the vascular abnormalities associated with this disorder.     

An electron microscopic study of the processes of nerve regeneration after lyophilized nerve homografting

The objective of the present study was to investigate the role of the Schwann cell basal lamina in nerve regeneration. To achieve this goal, we observed the process of axonal regeneration within a lyophilized nerve graft, in which only the basal lamina of the Schwann cell persisted. Sciatic nerves were removed from rats and lyophilized to kill the Schwann cells and other components. These grafts were transplanted to rat sciatic nerve defects. The rats were then killed after lapses of time. We observed the processes of axonal regeneration using a transmission electron microscope. Regeneration of axons along the inner surface of the Schwann cell basal lamina was clearly seen. These results suggest that, if tubular basal laminae persist, Schwann cells are not always necessary, and axonal regeneration can be induced in the direction toward the basal lamina.