Silicone-containing polymer blend electrolyte membranes for fuel cell applications

Polymer electrolyte membranes are developed from blends of chemically durable silicone-containing epoxy (Si-Epoxy) and proton conducting sulfonic polyimide (SPI). A charge-transfer (CT) complex is formed between electron-donating dihydroxynaphthalene units in Si-Epoxy, and electron-accepting naphthalenediimide units in SPI, as confirmed via X-ray diffraction and visible spectroscopy. The blend membranes show comparable mechanical strength to Nafion 211, but the elongation to break is much lower, indicating better resistance to deformation under strain stress, attributed to CT complex formation. The chemical durability of the blend membranes was much higher than pure SPI according to Fenton's test, also attributed to CT complex formation. Meanwhile, the proton conductivity is dependent on the sulfonic acid content of the SPI, which in turn affects the fuel cell performance. The maximum proton conductivity was measured to be 23.1 mS cm⁻¹ at 80°C and 90 %RH for a 1:1 blend, and the membranes were successfully incorporated into PEFCs.     

Combination of Near-Infrared Photoimmunotherapy Using Trastuzumab and Small Protein Mimetic for HER2-Positive Breast Cancer

Near-infrared photoimmunotherapy (NIR-PIT) is a promising cancer therapy based on a monoclonal antibody conjugated to a photosensitizer (IR700Dye) that is activated by near-infrared light irradiation. We previously reported on the use of NIR-PIT with a small protein mimetic, the Affibody molecule (6–7 kDa), instead of a monoclonal antibody. In this study, we investigated a combination of NIR-PIT for HER2-positive breast cancer cells (SK-BR3, MDA-MB361, and JIMT1) with HER2 Affibody-IR700Dye conjugate and trastuzumab-IR700Dye conjugate. HER2 Affibody and trastuzumab target different epitopes of the HER2 protein and do not compete. In vitro, the combination of NIR-PIT using both HER2 Affibody-IR700Dye conjugate and trastuzumab-IR700Dye conjugate induced necrotic cell death of HER2-positive breast cancer cells without damage to HER2-negative breast cancer cells (MCF7). It was more efficient than NIR-PIT using either the HER2 Affibody-IR700Dye conjugate alone or the trastuzumab-IR700Dye conjugate alone. Additionally, this combination of NIR-PIT was significantly effective against HER2 low-expressing cancer cells, trastuzumab-resistant cells (JIMT1), and brain metastatic cells of breast cancer (MDA-MB361). Furthermore, in vivo imaging exhibited the strong fluorescence intensity of both HER2 Affibody-IR700Dye conjugates and trastuzumab-Alexa488 conjugates in HER2-positive tumor, indicating that both HER2 Affibody and trastuzumab specifically bind to HER2-positive tumors without competing with each other. In conclusion, the combination of NIR-PIT using both HER2 Affibody and trastuzumab expands the targeting scope of NIR-PIT for HER2-positive breast cancer.     

X-ray absorption study on LiNi0.8Co0.15Al0.05O2 cathode material for lithium-ion batteries

LiNi_0.8Co_0.15Al_0.05O₂, being one of the promising cathode materials for lithium-ion batteries, shows distinct capacity fades after charge/discharge cycling and/or storage at high temperatures. The origin of the capacity fade has been explored by investigating the electronic and structural changes of the cathode material using X-ray absorption spectroscopy (XAS). Ni K-edge XAS measurements were performed in two different modes: surface-sensitive conversion electron yield (CEY) mode and bulk-sensitive transmission mode. Ni K-edge XANES data revealed that, after the cycling and aging tests, the bulk-averaged Ni valences were reduced, implying the existence of divalent Ni atoms. Further reductions of Ni atoms were observed at the surface of the cathode material particles, and the ranges of the Ni valence change upon charging became narrower, indicating the existence of the Ni atoms that did not oxidize. These changes which occur prominently at the surface are probably the main causes of the capacity fade.     

Relationship between the gas transport properties and the refractive index in high‐free‐volume fluorine‐containing polyimide membranes

The refractive index and gas transport properties (i.e., permeability, diffusivity, and solubility) in the 2,2′‐bis(3,4‐dicarboxyphenyl) hexafluoropropane dianhydride (6FDA)‐based polyimides were systematically investigated in terms of their polymer fractional free volumes (FFVs). The permeability and diffusion coefficients of the 6FDA‐based polyimide membranes to hydrogen, oxygen, nitrogen, methane, and carbon dioxide were correlated with their FFVs, which were estimated with van Krevelen's group contribution method. Linear correlations were also observed between the gas transport properties and the refractive index of these polyimides. We described FFV as a function of the refractive index based on the Lorentz–Lorenz equation. Linear correlations were observed between their refractive‐index‐based FFVs and the gas permeability, diffusivity, and solubility coefficients of these 6FDA‐based polyimides membranes. However, the FFVs of the 6FDA‐based polyimides calculated from refractive index were 1.16–1.37 times larger than their FFV values. This FFV was dependent on the free‐volume space and optical factors, such as the refractive index and molar refraction, which affected the electronic structure and the interactions between the gas molecules and the polymer segments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Uphill and selective transport of uranyl ions through 2,3-epithiopropyl methacrylate–2-acrylamide-2-methyl propane sulfonic acid copolymer membranes

Cation exchange membranes were prepared with 2,3-epithiopropyl methacrylate (ETMA)-2-acrylamide-2-methylpropane sulfonic acid (AMPS) copolymers. Transport of uranyl ion against its concentration gradient through the membranes was investigated by using a system containing carbonate solution (left side) and uranyl ion (and other metal ion) solution (right side). ETMA–AMPS copolymer membranes transported UO²⁺₂ against its concentration gradient. Na₂CO₃ solution was most effective as receiving solution for the uphill transport of UO²⁺₂. The transport was greatly affected by the composition of the copolymer membranes. Highly selective transport of UO²⁺₂ from the solution containing UO²⁺₂ and other metal ions was observed by using Na₂CO₃ solution in the left side. The main driving force for this transport of UO²⁺₂ is the high complex-formation ability of UO²⁺₂ with CO^2?₃.     

Numerical analysis of a reactive extrusion process. Part I: Kinetics study on grafting of vinylsilane to polyethylene

For controlling a reactive extrusion process in the subsequent study. the model equations of reaction kinetics and shear viscosity were studied. We focused on a free radical reaction between the molten polyethylene and vinylsilane. The kinetics model was expressed as a reaction rate equation with an apparent rate constant. The shear dependent of reacted polyethylene was formulated by employing the modified Cross model proposed in our early study. In addition, the average molecular weight was considered to correlate the shear viscosity with the reaction kinetics, leading to a series of rheo‐kinetics formulas. The experiments were carried out in a specific batch mixer suitably designed for sampling in arbitrary periods. Their reaction conversions, molecular weight distributions, and shear viscosity were measured, respectively, with an induced coupled plasma (ICP) emission spectrochemical analyzer, a high temperature gel permeation chromatography (GPC), and a capillary rheometer. Determining the parameters in each model, a simulator is set to investigate an engineering extrusion process.     

Simultaneous determination of paracetamol and ascorbic acid using tetraoctylammonium bromide capped gold nanoparticles immobilized on 1,6-hexanedithiol modified Au electrode

Tetraoctylammonium bromide stabilized gold nanoparticles (TOAB-AuNPs) attached to 1,6-hexanedithiol (HDT) modified Au electrode was used for the simultaneous determination of paracetamol (PA) and ascorbic acid (AA) at physiological pH. The attachment of TOAB-AuNPs on HDT modified Au surface was confirmed by attenuated total reflectance (ATR)-FT-IR spectroscopy and atomic force microscope (AFM). The ATR-FT-IR spectrum of TOAB-AuNPs attached to the HDT monolayer showed a characteristic stretching modes corresponding to -CH₂ and -CH₃ of TOAB, confirming the immobilization of AuNPs with surface-protecting TOAB ions on the surface of the AuNPs after being attached to HDT modified Au electrode. AFM image showed that the immobilized AuNPs were spherical in shape and densely packed to a film of ca. 7 nm thickness. Interestingly, TOAB-AuNPs modified electrode shifted the oxidation potential of PA towards less positive potential by 70 mV and enhanced its oxidation current twice when compared to bare Au electrode. In addition, the AuNPs modified electrode separated the oxidation potentials of AA and PA by 210 mV, whereas bare Au electrode failed to resolve them. The amperometry current of PA was increased linearly from 1.50 × 10⁻⁷ to 1.34 × 10⁻⁵ M with a correlation coefficient of 0.9981 and the lowest detection limit was found to be 2.6 nM (S/N = 3). The present method was successfully used to determine the concentration of PA in human blood plasma and commercial drugs.     

Aquatic toxicity and biodegradability of advanced cationic surfactant APA-22 compatible with the aquatic environment

Cationic surfactant is a chemical substance used in hair conditioner, fabric softener and other household products. By investigating the relationship between the aquatic toxicity and the chemical structures of two types of mono alkyl cationic surfactants, alkyl trimethylammonium salts and alkyl dimethylamine salts, we have found that the C22 alkyl chain length is effective to reduce the toxicity. Besides, we have recognized that the amidopropyl functional group contributes to the enhanced biodegradability by investigating the biodegradation trend of (alkylamidopropyl)dimethylamine salt (alkyl chain length: C18). Based on these findings, we have developed mono alkyl cationic surfactant called APA-22, N-[3-(dimethylamino)propyl]docosanamide salt. APA-22 is formed by the C22 alkyl chain, amidopropyl functional group and di-methyltertiary amine group. We evaluated the aerobic and anaerobic biodegradability of APA-22 by two standard methods (OECD Test Guideline 301B and ECETOC technical document No.28) and found that this substance was degraded rapidly in both conditions. The toxicity to algae, invertebrate and fish of this substance are evaluated by using OECD Test Guideline 201, 202 and 203, respectively. All acute toxicity values are >1 mg/L, which indicates that environmental toxicity of this substance is relatively less toxic to aquatic organism. In addition, we estimated the biodegradation pathway of APA-22 and observed the complete disappearance of APA-22 and its intermediates during the test periods. Based on the environmental data provided above, we concluded that APA22 is more compatible with the aquatic environment compared to other cationic surfactants with mono long alkyl chain.     

Synthesis of polymer gel with chiral helical cavity by molecular imprinting using bifunctional vinyl monomers

The molecular imprinting method was applied for synthesizing gels with a chiral helical cavity using various bifunctional vinyl monomers, such as α-(benzyloxymethyl)acrylic acid derivatives as a monomer, and one-handed helical (+)-poly(diphenyl-2-pyridylmethyl methacrylate) as a template. The chiral gels were almost quantitatively prepared after removal of the template polymer by hydrolysis of the ester groups. The obtained gels exhibited chiral resolution powers toward various racemates, such as trans-stilbene oxide and Tröger's base, and the substituents on the phenyl group of the monomer significantly affected the recognition ability. The observed separation factors were higher than those of the gels prepared from the mono-functional vinyl monomer, methacrylic acid.     

Deposition from the vapour phase during induction plasma treatment of alumina powders

A study was carried out of the induction plasma melting of alumina powders (particle mean diameter, ¯d _p=24.5 m), (Ar/H₂ or Ar/N₂ plasma, plate power, 40 kW) under reduced pressure conditions (400 torr). The results reveal that in the process, partial vaporization of the alumina powders takes place in the hot region of the discharge. As the molten particles cool down and solidify, the deposits from the vapour phase was formed with the spheroidized particles. In all treatments with the Ar/H₂ and Ar/N₂ plasmas, a condensate of ultrafine alumina fume (d _p<200 nm) was obtained. The fine particles consisted essentially of metastable -, - and -phases. Needle-like crystals(0.1–0.3 m diameter, by 5–15 m long) were observed when operating with an Ar/N₂ plasma at powder feed rates exceeding 10 g min^–1. Electron diffraction analysis revealed that the needles were whiskers, whose structure was very similar to - or -aluminas with an hexagonal close-packed oxygen lattice. The change of morphology is related to the degree of supersaturation in the vapour phase.