Study of deep oxidation and sulfonation of graphene oxide as low-temperature fuel cell electrolyte

In order improve the fuel cell performance of a free-standing graphene oxide (GO) membrane, the impacts of both the additional oxidation of GO and the modification with vinilsulfonic acid were investigated. The modification with vinilsulfonic acid was conducted with and without adding potassium persulfate, K₂S₂O₈, which is a radical initiator for the polymerization of vinylsulfonate. A total of six types of free-standing GO membranes with and without the oxidation and/or the modification were prepared. The oxidation and the modification additively increased the proton conductivity, and the oxidation significantly improved the durability of the fuel cell performance at 30 °C. The membrane of GOhvsi, of which GO was oxidized and modified with the initiator, showed very high in-plane proton conductivities at 30 °C, i.e., 0.54 S cm^?1 at RH 100%. The H₂–O₂ fuel cell using GOhvsi showed maximum power densities as high as 136 mW cm^?2 and 184 mW cm^?2 at 30 °C and 50 °C, respectively. The performance at 30 °C was stable for more than 20 h. The improved durability by the oxidation was attributed to the increased defects of carbon based on an XPS analysis. The TPD-MS analysis suggested that the oxygenated functional groups at the defects would increase the binding strength.     

Defects of structure in one-dimensional trains of drops of alternating composition

Merging two periodic droplet trains at a T-junction, we investigate the production of one-dimensional trains of drops of alternating composition. The structure of these trains consists of a succession of well-defined patterns and defects. A discrete model recently introduced to describe the structure of double emulsions made with two-step microfluidic dripping techniques predicts the nature of these patterns and their scheme of arrangement in a train as functions of the rates at which the two droplet trains reach the junction. Millifluidic experiments validate these predictions.     

Novel SiO2-deposited CaF2 substrate for vibrational sum-frequency generation (SFG) measurements of chemisorbed monolayers in an aqueous environment

A novel SiO(2)-deposited CaF(2) (SiO(2)/CaF(2)) substrate for measuring vibrational sum-frequency generation (SFG) spectra of silane-based chemisorbed monolayers in aqueous media has been developed. The substrate is suitable for silanization and transparent over a broad range of the infrared (IR) probe. The present work demonstrates the practical application of the SiO(2)/CaF(2) substrate and, to our knowledge, the first SFG spectrum at the solid/water interface of a silanized monolayer observed over the IR fingerprint region (1780-1400 cm(-1)) using a back-side probing geometry. This new substrate can be very useful for SFG studies of various chemisorbed organic molecules, particularly biological compounds, in aqueous environments.     

Strain-time effects in low-cycle fatigue of nickel-base heat-resistant alloys at high temperature

A series of strain controlled low-cycle fatigue tests in the simulated high-temperature gas-cooled reactor (HTGR) helium environment were conducted at 900°C on Hastelloy X and its modified version, Hastelloy XR. In those tests the effects of strain rate and hold time on high-temperature low-cycle fatigue behavior were investigated. Decreasing the strain rate led to notable reductions in the fatigue life. In the tests with the trapezoidal strain waveform, the fatigue life was found to be reduced most effectively in tensile hold-time experiments. The tendency was interpreted through the feature of the crack morphology.     

A two-color tunable infrared/vacuum ultraviolet spectrometer for high-resolution spectroscopy of molecules in molecular beams

We describe here the key technical elements of a two-color tunable IR/VUV photoionization TOF mass spectrometer system which allows a wide-range of high-resolution experiments to be performed on a diverse range of cold molecules and clusters in a molecular beam. In particular we highlight the methods we have applied to provide efficient wavelength separation of the VUV radiation from the longer wavelength components used to generate it and discuss a number of systems that we have studied with the instrument which highlight its flexibility for use in the study of molecular spectroscopy.     

Preparation of lateral spin-valve structure using doped conducting polymer poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)

To perform four-terminal nonlocal spin-valve measurements on organic spin-valves, we fabricated lateral spin-valve devices consisting of doped conducting polymer poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) [PEDOT:PSS] and ferromagnetic Ni₈₀Fe₂₀ narrow line (width: 530 nm) electrodes. Although the formula of the nonlocal magnetoresistance with the parameters of doped conducting polymers predicts sufficient nonlocal magnetoresistance, we could not observe any spin signal. The spin diffusion length in the doped PEDOT:PSS device does not appear to be as long as those predicted by both the Elliott–Yafet mechanism and the theory of spin relaxation in organic disordered solids.     

Increased Water Resistance of Bamboo Flour/Polyethylene Composites

Abstract

To improve the water resistance of bamboo flour/high-density polyethylene (HDPE) composites, the effects of plastic content, coupling agents, and the addition of micro-fibrillated cellulose (MFC) on formulations were studied, and their rheological and mechanical properties were evaluated. The composites were prepared by injecting molding with a basic composition of equivalent amounts of bamboo flour and HDPE, and the melting fluidity of the compounds, tensile strength, and tensile modulus of the composites were determined. An increase in water resistance was detected in all three tests. By increasing the plastic content, negative effects such as a decreased tensile modulus were observed. When evaluating the compatibility between bamboo flour and plastic using coupling agents and MFC addition, positive effects were noted for water resistance, melting fluidity, and tensile modulus. We also confirmed that the procedure used to increase the compatibility between bamboo flour and plastic could easily be used for industrial applications by changing the coupling agents. Overall, a novel positive property (increased tensile modulus) and an increased water resistance were observed after MFC addition.