Lipophilic polyelectrolyte gels as super-absorbent polymers for nonpolar organic solvents

Polyelectrolyte gels that are known as super-absorbent polymers swell and absorb water up to several hundred times their dried weights and have become ubiquitous and indispensable materials in many applications. Their superior swelling abilities originate from the electrostatic repulsion between the charges on the polymer chains and the osmotic imbalance between the interior and exterior of the gels. However, no super-absorbent polymers for volatile organic compounds (VOCs), and especially for nonpolar organic solvents (epsilon<10) have been reported, because common polyelectrolyte gels collapse in such solvents owing to the formation of a higher number of aggregates of ions and ion pairs. Here, we report that a novel class of polyelectrolyte gels bearing tetra-alkylammonium tetraphenylborate as a lipophilic and bulky ionic group swell in some nonpolar organic solvents up to 500 times their dry size. Dissociation of the ionic groups even in low-dielectric media (3相似文献   

Van Hove singularities as a result of quantum confinement: The origin of intriguing physical properties in Pb thin films

In situ angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling spectroscopy (STS) have been used to study the electronic structure of Pb thin films grown on a Si(111) substrates. The experiments reveal that the electronic structure near the Fermi energy is dominated by a set of m-shaped subbands because of strong quantum confinement in the films, and the tops of the m-shaped subbands form an intriguing ring-like Van Hove singularity. Combined with theoretical calculations, we show that it is the Van Hove singularity that leads to an extremely high density of states near the Fermi energy and the recently reported strong oscillations (with a period of two monolayers) in various properties of Pb films.     

Transient stability evaluation method based on kinetic energy of postfault trajectories

It is very important to maintain supply reliability in the deregulated environment. The transient stability problem is one of the major concerns in studies of planning and operation of power systems. Time domain simulation is currently the best available tool for allowing the use of detailed models and for providing reliable results. The main limitations of this approach involve long computation times. Therefore, this paper proposes a transient stability evaluation method using minimum transient kinetic energy of postfault trajectories. This method can estimate critical clearing times with only two points of the minimum transient kinetic energy, regardless of whether the trajectories after the clearing time are stable or unstable. The validity of the proposed method is shown by simulation studies with the IEEJ EAST 10‐machine 47‐bus system. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(3): 18–24, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21018     

KCNK10, a Tandem Pore Domain Potassium Channel,Is a Regulator of Mitotic Clonal Expansion during the Early Stage of Adipocyte Differentiation

KCNK10, a member of tandem pore domain potassium channel family, gives rise to leak K⁺ currents. It plays important roles in stabilizing the negative resting membrane potential and in counterbalancing depolarization. We previously demonstrated that kcnk10 expression is quickly elevated during the early stage of adipogenesis of 3T3-L1 cells and that reduction of kcnk10 expression inhibits adipocyte differentiation. However, the molecular mechanism of KCNK10 in adipocyte differentiation remains unclear. Here we revealed that kcnk10 is induced by 3-isobutyl-1-methylxanthine, a cyclic nucleotide phosphodiesterase inhibitor and a potent inducer of adipogenesis, during the early stage of adipocyte differentiation. We also demonstrated that KCNK10 functions as a positive regulator of mitotic clonal expansion (MCE), a necessary process for terminal differentiation. The reduction of kcnk10 expression repressed the expression levels of CCAAT/enhancer-binding protein β (C/EBPβ) and C/EBPδ as well as the phosphorylation level of Akt during the early phase of adipogenesis. In addition, knockdown of kcnk10 expression suppressed insulin-induced Akt phosphorylation. These results indicate that KCNK10 contributes to the regulation of MCE through the control of C/EBPβ and C/EBPδ expression and insulin signaling.     

A New Strategy for the Preparation of Terephthalic Acid by the Aerobic Oxidation of p‐Xylene using N‐Hydroxyphthalimide as a Catalyst

A new methodology for the production of terephthalic acid ( 3 ) by the aerobic oxidation of p‐xylene ( 1 ) using a combined catalytic system of N‐hydroxyphthalimide (NHPI)/Co(OAc) ₂/Mn(OAc) ₂was developed. The oxidation of 1 under a dioxygen atmosphere in the presence of a catalytic amount of NHPI/NHPI(OAc) ₂/Mn(OAc) ₂at 100 °C for 14 h afforded terephthalic acid in 82% yield. Removal of Mn(OAc) ₂ from the catalytic system resulted in considerable reduction in the yield of 3 . When the oxidation of 1 was carried out under a pressure of air (30 atm) at 150 °C, the reaction was completed within 3 h to give 3 in 84% yield. The oxidation of p‐toluic acid ( 2 ), which can be prepared by the oxidation of 1 using the NHPI/NHPI(OAc) ₂ system at room temperature, by the NHPI/NHPI(OAc) ₂/Mn(OAc) ₂system under pressure of air (30 atm) at 150 °C gave 3 in 95% yield. N‐Acetoxyphthalimide (NAPI) was found to require a lower catalyst loading than NHPI, but oxidation with NAPI was slower. Thus, the oxidation of 1 catalyzed by NAPI (5 mol %)/Co(OAc) ₂ (0.5 mol %)/Mn(OAc) ₂ (0.5 mol %) under a dioxygen atmosphere (1 atm) in acetic acid at 100 °C gave 3 in 80% yield.     

Skeletal Muscle Depletion Predicts the Prognosis of Patients with Hepatocellular Carcinoma Treated with Sorafenib

The aim of this study was to determine whether skeletal muscle depletion predicts the prognosis of patients with hepatocellular carcinoma (HCC) that is being treated with sorafenib. We evaluated 40 consecutive HCC patients who received sorafenib treatment. The skeletal muscle cross-sectional area was measured by computed tomography at the third lumbar vertebra (L3), from which the L3 skeletal muscle index (L3 SMI) was obtained. The factors contributing to overall survival, sorafenib dose reduction, and discontinuation of sorafenib were analyzed using the Cox proportional hazards model. L3 SMI (p = 0.020) and log (α-fetoprotein (AFP)) (p = 0.010) were identified as independent prognostic factors in HCC patients treated with sorafenib. The initial dose of sorafenib (p = 0.008) was an independent risk factor for sorafenib dose reduction, and log (AFP) (p = 0.008) was the only significant risk factor for the discontinuation of this drug. L3 SMI was not a risk factor for either dose reduction (p = 0.423) or the discontinuation (p = 0.132) of sorafenib. A multiple linear regression analysis determined the following relationship between skeletal muscle mass (assessed as L3 SMI) and the explanatory factors: L3 SMI = −0.1896 × (Age) − 10.3441 × (Child-Pugh score) − 9.3922 × (log (AFP)) + 1.6139 × (log (AFP)) × (Child-Pugh score) + 112.9166. Skeletal muscle depletion is inversely associated with age, Child-Pugh score, and log (AFP). Moreover, it is an independent prognostic factor for HCC patients treated with sorafenib.     

Local Fracture Toughness of Si3N4 Ceramics Measured using Single‐Edge Notched Microcantilever Beam Specimens

Local fracture toughness gives us useful and important information to understand and improve mechanical properties of bulk ceramics. In this study, the local fracture toughness of silicon nitride (Si₃N₄) ceramics was directly measured using single‐edge notched microcantilever beam specimens prepared by the focused ion beam technique. The measured fracture toughness of grain boundary of the Si₃N₄ ceramics is higher than the fracture toughness of SiAlON glass, which exists in the grain boundaries of Si₃N₄ ceramics. It is also shown that the fracture toughness of grain boundary depends on the rare earth oxide added as a sintering aid, which is expected in terms of the difference in the grain‐boundary structure. The fracture toughness of a single β‐Si₃N₄ grains is higher than the grain‐boundary fracture toughness. It was also higher than the value estimated from ab initio calculations and surface energy, which means that any dissipative energy should be included in the fracture toughness of a grain in spite of the brittle fracture in Si₃N₄. The fracture toughness of polycrystals of Si₃N₄ ceramics measured using single‐edge notched microcantilever beam specimens is intermediate between those of grains and grain boundaries, and it agrees with the estimated initial value of the Rcurve, K_I0, in Si₃N₄ ceramics.     

Carbon foams prepared from polyimide using urethane foam template

Polyimide and carbon foams were successfully prepared using polyurethane foams as a template. Impregnation of polyimide precursor, poly(amide acid), followed by imidization at 200 °C gave polyurethane/polyimide (PU/PI) composite foams, which resulted in PI foams by heating above 400 °C and then carbon foams above 800 °C. Foams carbonized at 1000 °C were graphitized by the heat treatment at 3000 °C, keeping foam characteristics. Two applications of these carbon foams, i.e., an adsorbent of ambient water vapor and a substrate of photocatalyst anatase TiO₂, were experimentally confirmed. For the former application, the present foam could be characterized by prompt adsorption of ambient water vapor. Some of carbon foams prepared were floating on water, even after loading photocatalyst anatase, which might be advantageous for photodecomposition of pollutants in water in respect to the UV rays efficiency.     

Milling‐induced esterification between cellulose and maleated polypropylene

The ball milling of cellulose and maleic anhydride grafted polypropylene (MAPP) induced the formation of ester bonds between OH groups of cellulose and maleic anhydride groups of MAPP, in marked contrast to the melt mixing of the original cellulose and MAPP, through which the esterification was hardly observed. This esterification was hardly dependent on the chemical structure of MAPP. In agreement with the enhanced interfacial adhesion due to the formation of ester bonds, a composite prepared via ball milling revealed an improvement in the tensile strength with respect to a melt‐mixed composite. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1703–1709, 2004