Characterization and Mechanical Properties of Flexible Dimethylsiloxane-Based Inorganic/Organic Hybrid Sheets

Flexible large sheets of dimethylsiloxane-based inorganic/organic hybrids with sizes of ∼200 mm × 290 mm and ∼1.5 mm thickness have been fabricated from poly(dimethylsiloxane) (PDMS) and metal alkoxides of Zr and Ta. The hybrid sheets were characterized by XPS, EXAFS, FT-IR, HRTEM, and SAXS. The inorganic components derived from metal alkoxides in the dimethylsiloxane-based hybrid sheets were found to be present as oxide-like clusters with sizes of 2–3 nm or below, which were chemically attached to PDMS via M–O–Si bonds. The hybrid sheets showed high elongation, strength, and thermal stability. A high elongation of about 100% was observed in the hybrid sheets fabricated in Zr(OBuⁿ)₄/PDMS = 2 at 180°C and a high tensile strength of about 3.0 MPa was observed in those fabricated in Zr(OBuⁿ)₄/PDMS = 4 at 180°C. The flexibility of the hybrid sheets was kept at least to 200°C for 100 h in N₂. These features are thought to come from the inorganic components derived from metal alkoxides, which are close to the molecular-level size and behave as a strong cross-linking agent of PDMS chains.     

α-Glucosidase Inhibition Activity by Cyclic Diarylheptanoids from Alnus sieboldiana

Abstract

A diarylheptanoid, named 3,17-dihydroxy-tricyclo[12.3.1.1^2,6]nonadeca- 1(18),2,4,6(19),14,16-hexaen-9,11-dione, was newly isolated from the branch wood of Alnus sieboldiana, together with two known diarylheptanoids. The chemical structure of this compound was assigned on the basis of the NMR and MS data, information obtained though 1D- and 2D-NMR analyses. These three diarylheptanoids were found to significantly inhibit the activity of α-glucosidase.     

Evaluation of O3/UV and O3/H2O2 as Practical Advanced Oxidation Processes for Degradation of 1,4-Dioxane

The degradation of 1,4-dioxane was investigated on a laboratory scale. The extents of degradation and/or removal of 1,4-dioxane by ozonation at pH 6–8, UV irradiation, aeration, and addition of H₂O₂ were very limited. On the other hand, the degradation of 1,4-dioxane by O₃/UV and O₃/H₂O₂ was accelerated compared with the above respective methods. The amounts of 1,4-dioxane degraded per amount of ozone consumed in O₃/UV and O₃/H₂O₂ were also higher than in ozonation. The amount of 1,4-dioxane degraded in O₃/UV was affected by the intensity of UV irradiation, and that in O₃/H₂O₂ was affected by the amount of H₂O₂ added only in the case of a high initial concentration of 1,4-dioxane.     

Synthesis and chemical properties of electrochromic π‐conjugated polyphenylenes with pendant viologen‐TCNQ salts

Polyphenylene (PP) with NH₂ side groups, namely, PFluNH ₂ , was synthesized by the Pd‐catalyzed reaction of 2,5‐dibromoaniline with 9,9‐dihexylfluorene‐2,7‐diboronic acid bis(1,3‐propanediol) ester. The reaction of PFluNH ₂ with 1‐hexyl‐1′‐(2,4‐dinitrophenyl)‐4,4′‐bipyridinium diiodide ( SaltBPy(I^?) ) eliminated 2,4‐dinitroaniline to yield PPs with viologen (1,1′‐disubstituted 4,4′‐bipyridinium dications), PFluBPy(I^?) . The reaction of PFluBPy(I^?) with Li⁺TCNQ ^? resulted in anion exchange between Cl ^? and TCNQ ^? , and yielded PFluBPy(TCNQ^?) . The reaction of PFluBPy(TCNQ^?) with the neutral TCNQ⁰ resulted in an interaction between TCNQ ^? and TCNQ⁰, and yielded PFluBPy(TCNQ^?‐TCNQ⁰) . Cyclic voltammetry measurements suggested that an electrochemical reduction of the viologen moiety and oxidation of the polymer backbone within PFluBPy(TCNQ^?) and PFluBPy(TCNQ^?‐TCNQ⁰) . Furthermore, this reaction was accompanied by electrochromism. The electric conductivities (σ) of the pellets molded from PFluBPy(TCNQ^?) to PFluBPy(TCNQ^?‐TCNQ⁰) were 2.7 × 10 ^{? 4} and 4.2 × 10 ^{? 4} Scm ^{? 1}, respectively; these σ values were higher than that observed for PFluNH ₂ (σ < 10 ^{? 8} Scm ^{? 1}) due to the self‐doping in the polymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Strain-induced martensitic transformation near twin boundaries in a biomedical Co–Cr–Mo alloy with negative stacking fault energy

Biomedical Co–Cr–Mo (CCM) alloys have been commonly used for artificial hip and knee joint prostheses, but a need to improve their biomedical inertness and wear resistance has become widely recognized. The mechanical behavior of CCM alloys is dominated by strain-induced martensitic transformation (SIMT), which causes crack initiation during plastic deformation but dramatically enhances the wear resistance in practical use. To develop more reliable CCM alloys it is essential to clarify the factors affecting the occurrence of SIMT. In the present study we have focused on the effect of annealing twin boundaries (ATBs) on SIMT behavior. We have analyzed in detail the substructures near a parallel pair of ATBs after deformation under a stress preferential for slip parallel to the ATBs. Preferential formation of ε-hexagonal close-packed (HCP) phase at ATBs in metastable γ-face-centered cubic (FCC) phase was found by both scanning electron microscopy with electron backscattered diffraction (EBSD) analysis and transmission electron microscopy (TEM). High resolution TEM images indicated that thickening of the ε-HCP phase does not proceed regularly on every second atomic plane, which would form perfect ε-phase HCP structure, but irregularly leaving a high density of stacking faults. Furthermore, the thickness of the ε-HCP phase was found to be different at ATBs on the two sides of the twin. The difference was attributed to the internal stress due to strain incompatibility at the ATBs on the basis of residual stress analysis by the EBSD–Wilkinson method and phase-field simulation of solute segregation at ATBs.     

Hydrogen storage in trimethylamine hydrate: Thermodynamic stability and hydrogen storage capacity of hydrogen+trimethylamine mixed semi-clathrate hydrate

The thermodynamic stability and hydrogen occupancy for the hydrogen+trimethylamine mixed semi-clathrate hydrate system were investigated by means of phase equilibrium (pressure–temperature) measurements and Raman spectroscopic analyses. The hydrogen molecule gradually advanced to occupy the empty small cage of trimethylamine hydrate in proportion to pressure increase. Almost all small cages were filled up with the hydrogen molecules at about 80 MPa. Isothermal Raman spectroscopic analysis showed that the absorption-rate of hydrogen to the pre-treated trimethylamine hydrate was comparable to those of tetrahydrofuran hydrate. Only one hydrogen molecule was enclosed with one small cage at the equilibrium state in pre-treated trimethylamine hydrate.     

Characterization of 2-Fluoro-2’-deoxyadenosine in Duplex,G-Quadruplex and i-Motif

Among various kinds of fluorine-substituted biomolecules, 2-fluoroadenine (2FA) and its derivatives have been actively investigated as therapeutic reagents, radio-sensitizers, and ¹⁹F NMR probes. In spite of their excellent properties, DNA containing 2FA has not been studied well. For fundamental understanding and future applications to the development of functional nucleic acids, we characterized 2FA-containing oligonucleotides for canonical right-handed DNA duplex, G-quadruplex, and i-motif structures. Properties of 2FA were similar to native adenine due to the small size of the fluorine atom, but it showed unique features caused by high electronegativity. This work provides useful information for future application of 2FA-modified DNA.     

The Role of Leaky Gut in Nonalcoholic Fatty Liver Disease: A Novel Therapeutic Target

The liver directly accepts blood from the gut and is, therefore, exposed to intestinal bacteria. Recent studies have demonstrated a relationship between gut bacteria and nonalcoholic fatty liver disease (NAFLD). Approximately 10–20% of NAFLD patients develop nonalcoholic steatohepatitis (NASH), and endotoxins produced by Gram-negative bacilli may be involved in NAFLD pathogenesis. NAFLD hyperendotoxicemia has intestinal and hepatic factors. The intestinal factors include impaired intestinal barrier function (leaky gut syndrome) and dysbiosis due to increased abundance of ethanol-producing bacteria, which can change endogenous alcohol concentrations. The hepatic factors include hyperleptinemia, which is associated with an excessive response to endotoxins, leading to intrahepatic inflammation and fibrosis. Clinically, the relationship between gut bacteria and NAFLD has been targeted in some randomized controlled trials of probiotics and other agents, but the results have been inconsistent. A recent randomized, placebo-controlled study explored the utility of lubiprostone, a treatment for constipation, in restoring intestinal barrier function and improving the outcomes of NAFLD patients, marking a new phase in the development of novel therapies targeting the intestinal barrier. This review summarizes recent data from studies in animal models and randomized clinical trials on the role of the gut–liver axis in NAFLD pathogenesis and progression.     

Role of Neuroinflammation and Blood-Brain Barrier Permutability on Migraine

Currently, migraine is treated mainly by targeting calcitonin gene-related peptides, although the efficacy of this method is limited and new treatment strategies are desired. Neuroinflammation has been implicated in the pathogenesis of migraine. In patients with migraine, peripheral levels of pro-inflammatory cytokines, such as interleukin-1β (IL-1β) and tumor necrosis factor-α, are known to be increased. Additionally, animal models of headache have demonstrated that immunological responses associated with cytokines are involved in the pathogenesis of migraine. Furthermore, these inflammatory mediators might alter the function of tight junctions in brain vascular endothelial cells in animal models, but not in human patients. Based on clinical findings showing elevated IL-1β, and experimental findings involving IL-1β and both the peripheral trigeminal ganglion and central trigeminal vascular pathways, regulation of the Il-1β/IL-1 receptor type 1 axis might lead to new treatments for migraine. However, the integrity of the blood-brain barrier is not expected to be affected during attacks in patients with migraine.     

Enhanced decision making mechanism of rule-based genetic network programming for creating stock trading signals

Evolutionary computation generally aims to create the optimal individual which represents optimal action rules when it is applied to agent systems. Genetic Network Programming (GNP) has been proposed as one of the graph-based evolutionary computations in order to create optimal individuals. GNP with rule accumulation is an extended algorithm of GNP, which extracts a large number of rules throughout the generations and stores them in rule pools, which is different from general evolutionary computations. Concretely, the individuals of GNP with rule accumulation are regarded as evolving rule generators in the training phase and the generated rules in the rule pools are actually used for decision making. In this paper, GNP with rule accumulation is enhanced in terms of its rule extraction and classification abilities for generating stock trading signals considering up and down trends and occurrence frequency of specific buying/selling timing. A large number of buying and selling rules are extracted by the individuals evolved in the training period. Then, a unique classification mechanism is used to appropriately determine whether to buy or sell stocks based on the extracted rules. In the testing simulations, the stock trading is carried out using the extracted rules and it is confirmed that the rule-based trading model shows higher profits than the conventional individual-based trading model.