An etching characterization method for revealing the plastic deformation zone in a SUS303 stainless steel

Etching characteristics used to reveal localized plastic deformation zones in a SUS303 stainless steel have been examined. The etching was conducted on a sample using an etchant consisting of 5-g ferric chloride, 50-mL hydrochloric acid, and 100-mL water. The sample was deformed severely and heated to various temperatures before the etching process. With this etching technique, the plastically deformed area is clearly observed even at low magnification. This is due to a change of the microstructural characteristics in the plastic deformation zone. There are different microstructure patterns that reveal the plastic zone in the sample with and without heating, e.g., plastic zone in the sample with heating to 800 °C is observed clearly due to randomly oriented crystals and recrystallized small grains with precipitated nano-size particles. Details of the etching characteristics that reveal the plastic deformation zone are further discussed.     

Wood‐derived phenol novolaks and their wood/epoxy biocomposites

Guaiacol novolak (GCN) and wood‐tar creosote novolak (WCN) were synthesized by the reactions of wood‐derived guaiacol and creosote with formalin, respectively, and used as hardeners of sorbitol polyglycidyl ether (SPE). Thermal and mechanical properties of the cured resins (SPE‐GCN and SPE‐WCN) and their biocomposites with wood flour (WF) were compared with those of the materials prepared by using a petroleum‐based phenol novolak (PN). Although tan δ peak temperatures of SPE‐GCN and SPE‐WCN were lower than that of SPE‐PN, that (58.5–70.8°C) of SPE‐GCN/WF(40–50 wt %) was higher than that (56.6–57.0°C) of SPE‐PN/WF(40–50 wt %). Tensile moduli of all the biocomposites increased by the addition of WF, while tensile strengths were rather reduced. When the biocomposites with the same WF content were compared, tensile modulus of SPE‐GCN/WF was higher than that of SPE‐PN/WF. The 5% weight loss temperatures (346–291°C) of SPE‐GCN and SPE‐GCN/WF were comparable to those (338–284°C) of SPE‐PN and SPE‐PN/WF. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41347.     

SANS studies on catalyst ink of fuel cell

The structure of solid polymer electrode and catalyst ink of fuel cell has been investigated by focusing‐ (FSANS) and contrast‐variation small‐angle neutron scattering (CV‐SANS). The solid polymer electrode, consisting of carbon (C), platinum, and ionomer (polymer, P), exhibited a power‐law function with two asymptotes, i.e., from I(q) ～ q^?1 to I(q) ～ q^?4 with a crossover around q ≈ 0.005 Å^?1. The scattering functions of the catalyst ink, i.e., the polymer electrodes dispersed in water, were successfully decomposed to the corresponding partial structure factors, S_CC(q), S_PP(q), S_CP(q), exclusively representing C‐C, P‐P, and C‐P correlations. S_CC(q) was a monotonic decreasing function of q, dominating in the scattering from carbon clusters. On the other hand, S_PP(q) exhibited a scattering maximum characteristic of polyelectrolyte solutions. This suggests that ionic clusters in polyelectrolyte solutions are formed in catalyst ink. The cross term, S_CP(q), indicated that the carbon scattering is dominant and significant amount of ionomer is adsorbed on the carbon agglomerates. It is concluded that the catalyst ink consists of carbon agglomerates surrounded by ionomers and the presence of ionic‐cluster path plays a key role in the performance of the solid polymer electrodes in polymer electrolyte fuel cells. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39842.     

Effect of the solvent on growth of titania nanotubes prepared by anodization of Ti in HCl

The effect of the solvent on the anodic growth of titania nanotubes in HCl dissolved in water, ethylene glycol and 2-propanol was studied. These nanotubes grow with locally rapid breakdown of the passive TiO₂ film forming a forest of nanotubes-bearing microtowers with the background of passive TiO₂ Film. These bundles of assembled-groups of titania nanotubes look like Pillars corals. The low relative permittivity of the 2-propanol led to lowering of dissociation of HCl and hence lowering the activity of H⁺ and Cl⁻ ions which in turn led to suppress of dissolution of titania and increasing the growth rate of the titania nanotubes. The X-ray diffraction pattern showed that the titania nanotubes after annealing change to the crystalline anatase phase. The anodic films showed characteristic coloration with intensity and color that changes (qualitatively) with time of anodization.     

Shape-memory surface with dynamically tunable nano-geometry activated by body heat

Shape-memory surfaces with on-demand, tunable nanopatterns are developed to observe time dependent changes in cell alignment using temperature-responsive poly(?-caprolactone) (PCL) films. Temporary grooved nanopatterns are easily programmed on the films and triggered to transition quickly to permanent surface patterns by the application of body heat. A time-dependent cytoskeleton remodeling is also observed under biologically relevant conditions.     

Novel temperature-responsive polymer brushes with carbohydrate residues facilitate selective adhesion and collection of hepatocytes

Temperature-responsive glycopolymer brushes were designed to investigate the effects of grafting architectures of the copolymers on the selective adhesion and collection of hypatocytes. Homo, random and block sequences of N-isopropylacrylamide and 2-lactobionamidoethyl methacrylate were grafted on glass substrates via surface-initiated atom transfer radical polymerization. The galactose/lactose-specific lectin RCA₁₂₀ and HepG2 cells were used to test for specific recognition of the polymer brushes containing galactose residues over the lower critical solution temperatures (LCSTs). RCA₁₂₀ showed a specific binding to the brush surfaces at 37 °C. These brush surfaces also facilitated the adhesion of HepG2 cells at 37 °C under nonserum conditions, whereas no adhesion was observed for NIH-3T3 fibroblasts. When the temperature was decreased to 25 °C, almost all the HepG2 cells detached from the block copolymer brush, whereas the random copolymer brush did not release the cells. The difference in releasing kinetics of cells from the surfaces with different grafting architectures can be explained by the correlated effects of significant changes in LCST, mobility, hydrophilicity and mechanical properties of the grafted polymer chains. These findings are important for designing ‘on–off’ cell capture/release substrates for various biomedical applications such as selective cell separation.     

Velocity measurements of reactive and non‐reactive flows by NO‐LIF method using NO2 photodissociation

Velocities of reactive and non‐reactive flows, where NO₂ molecules were seeded, were measured by a NO‐based Laser Induced Fluorescence (LIF) method. NO₂ dilute gases were injected from a round tube with an inner diameter of 2 cm and its flow rate was 10 liters/minute or 20 liters/minute. Experiments were performed for 4 conditions—non‐reactive flows of NO₂ dilute gases at two flow rates, an unburnt gas flow of the premixed flame with NO₂ addition, and an unburnt gas flow of the diffusion flame with NO₂ addition. NO molecules were produced in flows by planar emissions of 355 nm laser rays from an Nd:YAG laser system, and NO‐LIF images were taken in a pre‐determined delay. An ICCD camera, a dye laser excited by an excimer laser, and Nd:YAG laser were strictly synchronized by a pulse generator. NO‐LIF signals, which were emitted by photochemically produced NO from NO₂, were strong enough to measure the NO displacements in the case of non‐reactive flows, while with only a few ppm concentrations of NO₂ added it was possible to measure the velocity in detail. Although fluctuations of NO trajectories were observed at the flow rate of 20 liters/minute, instantaneous velocities were measured accurately. In the case of the unburnt gas of the diffusion flame, NO‐LIF signals were also strong, and profiles of NO produced by NO₂ photodissociation were clearly measured. Profiles of NO produced by NO₂ photodissociation in the unburnt gas of the premixed flame were also clearly measured, even in the vicinity of the reaction zone. It can be seen that velocities were measured correctly in the unburnt regions of the premixed and the diffusion flames. With this method, it was possible to measure velocities of both steady and unsteady flows. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(1): 40–52, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20038     

Physical and electrochemical properties of Pt-Ru/C samples prepared on various carbon supports by using the barrel sputtering system

The present study investigated physical and electrochemical properties of carbon-supported Pt-Ru alloy (Pt-Ru/C) samples prepared on various carbon supports by using a sputtering system with barrel-type powder sample holder (the barrel sputtering system). For this system, the deposited Pt-Ru nano-particles had uniform sizes of less than 4 nm and homogeneous atomic ratios of Pt and Ru of ca. 50:50 at.% independent of a specific surface area of the carbon support. Further, the electrochemical properties of the prepared samples obtained from CO stripping voltammetry were almost identical. These were completely different from the result for wet process showing that the physical and electrochemical properties of samples prepared by an impregnation method changed with the specific surface area of the carbon support.     

Bio-based thermosetting bismaleimide resins using eugenol,bieugenol and eugenol novolac

5,5′-Bieugenol (BEG) and eugenol novolac (EGN) were synthesized by the oxidative coupling reaction of eugenol (EG) and the addition–condensation reaction of EG with formaldehyde, respectively. The EG, BEG and EGN were prepolymerized with 4,4′-bismaleimidediphenylmethane (BMI) at 180 °C and then compression-molded at finally 250 °C for 6 h to produce cured EG/BMI (EB), BEG/BMI (BB) and EGN/BMI (NB) resins with eugenol/maleimide unit ratios of 1/1, 1/2 and 1/3. The FT-IR analysis of EBs and ¹³C NMR analysis of the model reaction product of EG/N-phenylmaleimide (PMI) 1/3 at 200 °C for 12 h suggested that the ene reaction and subsequent Diels-Alder/ene reactions mainly occurred for EBs. The FT-IR analyses of BBs and NBs supported the occurrence of ene reaction and subsequent thermal addition copolymerization in a similar manner to the well-known curing reaction of 2,2′-diallylbisphenol A and BMI. The glass transition temperature (T_g) and 5% weight loss temperature (T₅) of the cured resin increased with increasing BMI content, and EB 1/3 showed the highest T_g 377 °C and T₅ 475 °C. The flexural strengths and moduli of EBs and NBs were higher than those of BBs, and EB 1/2 showed the most balanced flexural strength and modulus (84.5 MPa and 2.75 GPa). The FE-SEM analysis revealed that there is no phase separation for all the cured resins.     

Influences of miscible and immiscible oils on flow characteristics through capillary tube—part I: experimental study

A capillary tube is widely used as an expansion device for small refrigeration cycles. In a practical refrigeration cycle, some amount of refrigeration oil is discharged from a compressor and refrigerant/oil mixture flows through the capillary tube. This study investigated experimentally the influence of mixing of the refrigeration oil with the refrigerant on the flow through the capillary tube. The experiments are carried out with not only a miscible combination of refrigerant and oil but also an immiscible combination. In both cases, the mass flow rate through the capillary tube and temperature and pressure distributions along the tube are measured under several conditions of subcooled degree and oil concentration. In the case of miscible combination, the mass flow rate of refrigerant decreases with increasing the oil concentration because the viscosity of liquid phase increases by the mixing of viscous oil. Even in the case of the immiscible combination, the oil droplet is so small that it mixes homogeneously in the liquid phase in the capillary tube and the refrigerant mass flow rate decreases by the mixing of immiscible oil. There is no significant influence of the oil concentration on the underpressure, which means pressure difference between saturation pressure and flash inception pressure, in both miscible and immiscible combinations.