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71.
Yuanyuan Yang Honghao Zhang Satoshi Komasa Tetsuji Kusumoto Shinsuke Kuwamoto Tohru Okunishi Yasuyuki Kobayashi Yoshiya Hashimoto Tohru Sekino Joji Okazaki 《International journal of molecular sciences》2022,23(2)
Polyetheretherketone (PEEK) is a potential substitute for conventional metallic biomedical implants owing to its superior mechanical and chemical properties, as well as biocompatibility. However, its inherent bio-inertness and poor osseointegration limit its use in clinical applications. Herein, thin titanium films were deposited on the PEEK substrate by plasma sputtering, and porous nanonetwork structures were incorporated on the PEEK surface by alkali treatment (PEEK-TNS). Changes in the physical and chemical characteristics of the PEEK surface were analyzed to establish the interactions with cell behaviors. The osteoimmunomodulatory properties were evaluated using macrophage cells and osteoblast lineage cells. The functionalized nanostructured surface of PEEK-TNS effectively promoted initial cell adhesion and proliferation, suppressed inflammatory responses, and induced macrophages to anti-inflammatory M2 polarization. Compared with PEEK, PEEK-TNS provided a more beneficial osteoimmune environment, including increased levels of osteogenic, angiogenic, and fibrogenic gene expression, and balanced osteoclast activities. Furthermore, the crosstalk between macrophages and osteoblast cells showed that PEEK-TNS could provide favorable osteoimmunodulatory environment for bone regeneration. PEEK-TNS exhibited high osteogenic activity, as indicated by alkaline phosphatase activity, osteogenic factor production, and the osteogenesis/osteoclastogenesis-related gene expression of osteoblasts. The study establishes that the fabrication of titanate nanonetwork structures on PEEK surfaces could extract an adequate immune response and favorable osteogenesis for functional bone regeneration. Furthermore, it indicates the potential of PEEK-TNS in implant applications. 相似文献
72.
73.
Yoshinari Sawama Masahiro Masuda Ryosuke Nakatani Hiroki Yokoyama Yasunari Monguchi Toshifumi Dohi Yasuyuki Kita Hironao Sajiki 《Advanced Synthesis \u0026amp; Catalysis》2016,358(23):3683-3687
The iron(III) chloride‐catalyzed Friedel–Crafts arylation of 4‐aryl‐4‐methoxy‐2,5‐cyclohexadienones, which were easily prepared by the phenyliodine(III) diacetate (PIDA)‐mediated oxidation of 4‐arylphenols in methanol, proceeded site‐selectively to form meta‐terphenyl (2,4‐diarylphenol) derivatives in good yields. The subsequent PIDA‐mediated oxidation and iron(III) chloride‐catalyzed Friedel–Crafts arylation of the resulting products gave the corresponding 2,4,6‐triarylphenol derivatives. The present method provides useful highly substituted polyarylated compounds.
74.
Chitturi Venkateswara Rao Arava Leela Mohana Reddy Yasuyuki Ishikawa Pulickel M. Ajayan 《Carbon》2011,(3):931-936
Graphene-supported Pt and Pt3M (M = Co and Cr) alloy nanoparticles are prepared by ethylene glycol reduction method and characterized with X-ray diffraction and transmission electron microscopy. X-ray diffraction depicted the face-centered cubic structure of Pt in the prepared materials. Electron microscopic images show the high dispersion of metallic nanoparticles on graphene sheets. Electrocatalytic activity and stability of the materials is investigated by rotating-disk electrode voltammetry. Oxygen reduction activity of the Pt3M/graphene is found to be 3–4 times higher than that of Pt/graphene. In addition, Pt3M/graphene electrodes exhibited overpotential 45–70 mV lower than that of Pt/graphene. The high catalytic performance of Pt3M alloys is ascribed to the inhibition of formation of (hydr) oxy species on Pt surface by the alloying elements. The fuel cell performance of the catalysts is tested at 353 K and 1 atm. Maximum power densities of 790, 875, and 985 mW/cm2 are observed with graphene-supported Pt, Pt3Co, and Pt3Cr cathodes, respectively. The enhanced electrocatalytic performance of the Pt3M/graphene (M = Co and Cr) compared to that of Pt/graphene makes them a viable alternative to the extant cathodes for energy conversion device applications. 相似文献
75.
The sorption behavior of water vapor and CO2 gas in photocrosslinked poly(vinyl cinnamate) (PVCA) film was examined at 30°C under atmospheric pressure. Both the water sorption isotherm and the CO2 sorption isotherm obtained with quartz crystal microbalance (QCM) method obeyed the simple Langmuir's equation. Water vapor/CO2 mixed‐gas sorption isotherms were also obtained. Total amount of sorbed mixed gases was clearly influenced by the partial pressure of water vapor (pw) and CO2 gas (pc) in the atmosphere. A modified Langmuir's equation based on a dual‐site model was employed for predicting the competitive adsorption isotherm, and the isotherm was clearly described by the equation. The theoretically estimated amount of adsorbed water at the constant pw decreased slightly with increasing pc. The effect of this phenomenon on the sensitivity of the capacitive‐type relative humidity sensor was examined. As expected, the electrical capacitance of the sensor at the constant relative humidity decreased because of the coexistence of CO2 gas. However, the influence was quite small in the CO2 concentration range in the ordinary environment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 401–407, 2002 相似文献
76.
The recoverable shear strain (SR) for the liquid crystal‐forming hydroxypropyl cellulose solutions was determined by means of a concentric cylinder rotational apparatus as functions of shear stress prior to recovery and concentration of the solutions at 30°C. SR greatly depended on shear stress and concentration; the phase of the solution (the single phase or biphase) governed the dependences of SR on stress and concentration. SR increased with increasing stress for the single phase and decreased for the biphase. SR seemed to be related to the die swell (B): SR ∝ Bn. SR exhibited a maximum and a minimum with respect to concentration. SR for the cellulosic cholesteric liquid crystalline solutions was greater than that for the isotropic solutions. A model was proposed for explaining the greater SR. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 865–872, 2002 相似文献
77.
Blending a crosslinked high‐density polyethylene (xHDPE) enhances melt strength and strain hardening behavior in elongational viscosity of high‐density polyethylene (HDPE) to a great degree. Gel fraction of xHDPE has a stronger effect on the strain hardening than sol fraction, although sol fraction also enhances the strain hardening to some degree. Further, the xHDPE crosslinked by peroxide in a compression mold exhibits more pronounced effect than xHDPE by radiation, which is attributed to the difference in the amount of the gel fraction. The xHDPE, which enhances the strain hardening, has sparse crosslink points in the network. Moreover, it was found from linear viscoelastic measurements, such as oscillatory modulus and relaxation modulus, that the xHDPE is characterized as a critical gel, which was also supported by the result of tensile testing. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 73–78, 2002 相似文献
78.
Coconut shell-based activated carbon was oxidized in aq. H2SO4, HNO3 and H2O2 to induce surface oxygen functional groups on its surface and to increase the mechanical strength of the resultant activated carbon artifact with PVB as a binder. Although all oxidation was confirmed to significantly increase the strength, aq. H2O2 was found to be most effective, giving strength as high as 6000 kPa, which is believed to be sufficient for the electrode of an electric double layer capacitor (EDLC). The increase of CO2 evolving groups induced on the surface of activated carbon appears to be responsible for the strength increase. There was an optimum extent of oxidation for the strength as well as the performance of the electrode. Too much oxidation reduces the electrical conductivity of the activated carbon. Facile oxidation by aq. H2O2 can be recommended as a practical modification of the surface since it takes place safely below 100°C without releasing any harmful gas. 相似文献
79.
Layered -titanate materials, NaxMx/2Ti1−x/2O2 (M=Co, Ni and Fe, x=0.2–0.4), were synthesized by flux reactions, and electrical properties of polycrystalline products were measured at 300–800 °C. After sintering at 1250 °C in Ar, all products show n-type thermoelectric behavior. The values of both d.c. conductivity and Seebeck coefficient of polycrystalline Na0.4Ni0.2Ti0.8O2 were ca. 7×103 S/m and ca. −193 μV/K around 700 °C, respectively. The measured thermal conductivity of layered -titanate materials has lower value than conductive oxide materials. It was ca. 1.5 Wm−1 K−1 at 800 °C. The estimated thermoelectric figure-of-merit, Z, of Na0.4Ni0.2Ti0.8O2 and Na0.4Co0.2Ti0.8O2 was about 1.9×10−4 and 1.2×10−4 K−1 around 700 °C, respectively. 相似文献
80.
Electron beam (EB)-induced graft polymerization is advantageous for the surface modification of fabrics. We investigated the effect of monomer concentration and the addition of alkyl groups on the oil repellency of polyethylene terephthalate (PET) fabrics treated with monomers containing fluoroalkyl groups through EB-induced graft polymerization via pre-irradiation. We use 2-(perfluorohexyl) ethyl acrylate (FEA) and stearyl acrylate (SA(C18)) with long alkyl chains as vinyl monomers to induce reaction with radicals generated from EB irradiation. The weight gain and surface morphology of the PET fabrics change with the FEA monomer concentration. The uniformity of the EB-grafted PET fabric surface is determined at low monomer solution concentrations. Results of X-ray photoelectron spectroscopy analysis show that adding 0.1 mol/L of FEA monomer to the EB-grafted PET fabric yields the highest dodecane contact angle of 93.4° and a surface fluorine concentration of 39.8%. The addition of SA(C18) monomer to the FEA monomer decreases the dodecane contact angle by 77.5° and yields a surface fluorine concentration of 19.1%. EB graft polymerization via pre-irradiation results in a uniformly treated surface, and stable oil repellency is achieved when using solely the FEA monomer at a lower monomer concentration than that used in a similar irradiation method reportedly previously. 相似文献