Electrosynthesis of 2,7-linked polycarbazole derivatives to realize low-bandgap electroactive polymers

Poly(2,7-carbazole) derivatives have been synthesized because they have more extended conjugation lengths and lower energy bandgaps than poly(3,6-carbazole)s; however, few studies regarding electrochemical synthesis of poly(2,7-carbazole)s have been reported. Here, a series of N-alkylated-2,7-di(2-furyl)carbazoles, N-butyl-2,7-di(2-thienyl)carbazole, and N-butyl-2,7-di(2-(3,4-ethylenedioxthienyl))carbazole, were synthesized to obtain electroactive films of poly(2,7-carbazole) derivatives by electrochemical polymerization. Cyclic voltammetry revealed that these monomers have excellent polymerization activity, due to their low oxidation potentials (<0.57 V vs. ferrocene (Fc/Fc⁺)), and the corresponding polymers exhibit good redox properties. The energy bandgaps of the polymers obtained from optical absorption spectra range from 2.1 to 2.3 eV. Among the polymers, poly[N-butyl-2,7-di(2-(3,4-ethylenedioxthienyl))carbazole] shows the lowest bandgap energy of 2.1 eV, which is lower than that of previously reported poly(3,6-carbazole) analogues (2.4 eV). This polymer exhibits a significant color change from red in the oxidized state to blue in the reduced state during an electrochemical redox process. The electrochemical and optical properties of the monomers are dependent on external heteroaromatic rings attached to the 2 and 7 positions of the carbazole unit.     

Observation of metal on Si(0 0 1) by STM/STS and its consideration based on the first principles calculations

Local density of states (LDOS) is obtained by the first principles calculation based on the density functional theory on the Si(0 0 1)2 × 1 surface and on the surface with an Al dimer. At an Al dimer, LDOS has a high intensity in the conduction band region, which cannot be seen on the Si(0 0 1)2 × 1 surface. This tendency is observed in STS measurements as well. The possibility for a microelementary analysis is presented by applying this method to other metal atoms on the Si surface. Furthermore, it is pointed out that STS measurements should be always performed at the same tip-sample separation to obtain reproducible STS spectrums.     

Defects in Carbon-Rich Ferrite of Cold-Drawn Pearlitic Steel Wires

By means of X-ray line profile analysis and positron lifetime spectroscopy, densities of deformation-induced defects in carbon-rich ferrite of a series of cold-drawn pearlitic steel wires with true strains (ε) up to 5 are characterized. It is shown that both the dislocation densities and the vacancy cluster concentrations increase continuously with increasing ε. On the basis of the measured defect densities, values of defect hardening are estimated. The result shows that contributions of the defect hardening to the total tensile strength of the wires reach nearly 40 pct, which is mainly ascribed to the dislocation hardening. Chemical surroundings of the defects in the carbon-rich ferrite are investigated by coincidence Doppler broadening spectroscopy. The association of carbon with the defects in ferrite is demonstrated.     

Growth and microstructure of Ba β-alumina films by laser chemical vapor deposition

Ba β-alumina films were prepared by laser chemical vapor deposition. Mostly single-phase Ba β-alumina films were obtained at 1125–1200 K and for an Al/Ba molar ratio of 12.4–16.6. BaAl₂O₄ and α-Al₂O₃ were codeposited with Ba β-alumina under Ba- and Al-rich conditions, respectively. The Ba β-alumina films consisted of hexagonal grains, and the (1 1 0)-oriented Ba β-alumina films had a fin-like columnar structure. The highest deposition rate reached 120 μm h^?1 at around 1200 K. A thin layer of Ba-rich superstructure was formed on the surface of the (1 1 0)-oriented columnar grains.     

Supercritical CO2 extraction of pigment components with pharmaceutical importance from Chlorella vulgaris

BACKGROUND: Chlorella vulgaris is a green microalgae that contains various pigment components of carotenoids and chlorophylls. Supercritical CO₂ is widely used for extraction of pharmaceutical compounds because it is non‐oxic and easily separated from extracted material by simply depressurizing. In this work, pharmaceutical compounds from Chlorella vulgaris have been extracted using supercritical CO₂ with or without entrainer at various extraction conditions. RESULTS: Based on high performance liquid chromatography (HPLC) analysis, the extracts contained pigment components, such as lutein, β‐carotene, chlorophyll a and b. Higher extraction pressure and temperature promoted higher lutein extraction by supercritical CO₂. The optimum pressure and temperature for extraction were obtained as 50 MPa and 80 °C. Ethanol as an entrainer was more effective than acetone for the extraction of pigment components. Pigment components in the extract obtained by supercritical CO₂ with and without entrainer were compared with the extract obtained by a conventional extraction method. CONCLUSION: Supercritical CO₂ has been successfully applied for the extraction of pigment components from Chlorella vulgaris. Supercritical CO₂ enabled high selectivity for lutein extraction; however, the lutein yield was lower than that obtained by extraction using supercritical CO₂ with ethanol and soxhlet. Copyright © 2008 Society of Chemical Industry     

Construction of simulation model for spray flash desalination system

This paper describes a simulation model for a spray flash desalination system which makes fresh water from sea water by using the temperature difference between warm surface sea water and cool deep sea water. The spray flash desalination system can be modeled by using the energy conservation law and the mass conservation law. Simulation results of the model are compared with the experimental results and show the accuracy of the proposed simulation model. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(4): 9–17, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20975     

Thermotropic and Barotropic Phase Behavior of Phosphatidylcholine Bilayers

Bilayers formed by phospholipids are frequently used as model biological membranes in various life science studies. A characteristic feature of phospholipid bilayers is to undergo a structural change called a phase transition in response to environmental changes of their surroundings. In this review, we focus our attention on phase transitions of some major phospholipids contained in biological membranes, phosphatidylcholines (PCs), depending on temperature and pressure. Bilayers of dipalmitoylphosphatidylcholine (DPPC), which is the most representative lipid in model membrane studies, will first be explained. Then, the bilayer phase behavior of various kinds of PCs with different molecular structures is revealed from the temperature–pressure phase diagrams, and the difference in phase stability among these PC bilayers is discussed in connection with the molecular structure of the PC molecules. Furthermore, the solvent effect on the phase behavior is also described briefly.     

Arterial-venous carbon dioxide tension difference after hypothermic cardiopulmonary bypass

Arterial-venous carbon dioxide tension difference (Pv-aCO2) is known to become high after severe hemorrhage shock and resuscitation. We hypothesized that Pv-aCO2 might be high after cardiac surgery because of the oxygen debt occurred during hypothermic cardiopulmonary bypass (CPB). Blood pressure, cardiac index, hemoglobin, the arterial and mixed venous blood gases were repeatedly measured every 6 hours for 24 hours following cardiac surgery in 60 adult patients who underwent hypothermic CPB. Immediately after the surgery, Pv-aCO2 was extremely high, then gradually decreased to within normal ranges 12 hours later (8.0 +/- 2.9 mmHg vs 5.9 +/- 3.1 mmHg. p < 0.01). Factors which significantly correlated to Pv-aCO2 were cardiac index, oxygen delivery, minimum rectal temperature and duration of CPB. Oxygen debt during hypothermic CPB might cause significantly high Pv-aDO2. At least 12 hours were necessary to recover from anaerobic status to physiological condition.     

Corrosion of MgO—MgAl2O4 Spinel Refractory Bricks by Calcium Aluminosilicate Slag

Microstructural analysis of MgO—MgAl₂O₄ refractory bricks corroded at 1400–1450°C by calcium aluminosilicate slag reveals secondary spinel, monticellite, merwinite, and MgO as microscopic corrosion products, generally forming in this sequence as the brick is penetrated. The secondary spinel forms an incomplete layer close to (but not at) the MgO grain. Thermodynamic calculations are used to support a detailed model of the corrosion mechanism.