Cutting performance by surgical scissors of tubular soft tissues such as blood vessels

Current surgical scissors globally and significantly deform blood vessels when cutting them because of the softness and tubular shape of the vessels, which damages the cut site. In this study, cutting experiments were performed on tubular tissue phantoms, and finite element analysis was conducted to clarify the influence of the scissors configuration on the cutting characteristics. Based on the findings, a new scissors model with a four-bar linkage mechanism is proposed. Cutting experiments showed that the developed scissors significantly suppresses global deformation during cutting.     

Effects of substrate bias voltage and target sputtering power on the structural and tribological properties of carbon nitride coatings

Effects of substrate bias voltage and target sputtering power on the structural and tribological properties of carbon nitride (CN_x) coatings are investigated. CN_x coatings are fabricated by a hybrid coating process with the combination of radio frequency plasma enhanced chemical vapor deposition (RF PECVD) and DC magnetron sputtering at various substrate bias voltage and target sputtering power in the order of −400 V 200 W, −400 V 100 W, −800 V 200 W, and −800 V 100 W. The deposition rate, N/C atomic ratio, and hardness of CN_x coatings as well as friction coefficient of CN_x coating sliding against AISI 52100 pin in N₂ gas stream decrease, while the residual stress of CN_x coatings increases with the increase of substrate bias voltage and the decrease of target sputtering power. The highest hardness measured under single stiffness mode of 15.0 GPa and lowest residual stress of 3.7 GPa of CN_x coatings are obtained at −400 V 200 W, whereas the lowest friction coefficient of 0.12 of CN_x coatings is achieved at −800 V 100 W. Raman and XPS analysis suggest that sp³ carbon bonding decreases and sp² carbon bonding increases with the variations in substrate bias voltage and target sputtering power. Optical images and Raman characterization of worn surfaces confirm that the friction behavior of CN_x coatings is controlled by the directly sliding between CN_x coating and steel pin. Therefore, the reduction of friction coefficient is attributed to the decrease of sp³ carbon bonding in the CN_x coating. It is concluded that substrate bias voltage and target sputtering power are effective parameters for tailoring the structural and tribological properties of CN_x coatings.     

Bone bonding ability of a chemically and thermally treated low elastic modulus Ti alloy: gum metal

The gum metal with composition Ti–36Nb–2Ta–3Zr–0.3O, is free from cytotoxic elements and exhibits a low elastic modulus as well as high mechanical strength. We have previously demonstrated that this gum metal, once subjected to a series of surface treatments—immersion in 1 M NaOH (alkali treatment) and then 100 mM CaCl₂, before heating at 700 °C (sample: ACaH-GM), with an optional final hot water immersion (sample: ACaHW-GM)—has apatite-forming ability in simulated body fluid. To confirm the in vivo bioactivity of these treated alloys, failure loads between implants and bone at 4, 8, 16, and 26 weeks after implantation in rabbits’ tibiae were measured for untreated gum metal (UT-GM), ACaH-GM and ACaHW-GM, as well as pure titanium plates after alkali and heat treatment (AH-Ti). The ACaH-GM and UT-GM plates showed almost no bonding, whereas ACaHW-GM and AH-Ti plates showed successful bonding by 4 weeks, and their failure loads subsequently increased with time. The histological findings showed a large amount of new bone in contact with the surface of ACaHW-GM and AH-Ti plates, suggesting that the ACaHW treatment could impart bone-bonding bioactivity to a gum metal in vivo. Thus, with this improved bioactive treatment, these advantageous gum metals become useful candidates for orthopedic and dental devices.     

Applicability of performance improvement method of existing steel railway bridges by installing concrete decks

Steel railway bridges which exceed their design lifetime are increasing in Japan, and some of them have problems such as corrosion and fatigue. In this study, we proposed a method to improve the performance, such as the load-carrying capacity, of the existing steel railway bridges by installation of concrete decks. To figure out the applicability of the proposed method, we discussed the applicable range of span and the effect of stress reduction. Considering application into actual bridges, we proposed an installation method using pre-cast concrete decks and girder-deck connection with filler mortar and steel fasteners. Finally, we carried out loading tests of the connection with fasteners and bending tests of the applied girders. As a result, we found that the girder-deck connections have enough static capacity for lateral force and train loads, under the condition that the studs are installed and the gaps between the pre-cast decks are filled with mortar.     

Biophotofuel cell (BPFC) generating electrical power directly from aqueous solutions of biomass and its related compounds while photodecomposing and cleaning

A biophotofuel cell (BPFC) generating electrical power directly from aqueous solutions of biomass and its related compounds with simultaneous photodecomposition and cleaning was investigated. The BPFC had a nanoporous TiO₂ photoanode and an O₂-reducing cathode. As long as the compounds were either liquid or water-soluble they were photodecomposed and generated electrical power simultaneously. Various biomasses and related compounds such as glucose, amino acids, polysaccharides, proteins, lignin derivatives, cellulose derivatives and some polymers were investigated in the BPFC. Glucose was photodecomposed almost completely into CO₂ under O₂ within 20 h while generating electrical power. The incident photon-to-current conversion efficiency (IPCE) value of a 0.5 M glucose solution in the BPFC under O₂ was 29% based on the incident monochromatic light at 350 nm (intensity 3.6 mW cm⁻²). A glycine aqueous solution could be decomposed photochemically into CO₂/N₂ in a nearly stoichiometric 4:1 (CO₂:N₂) molar ratio. The photodecomposition yield of 0.01 wt% lignosulfonic acid sodium salt was 86.5% in 24 h as estimated from the CO₂ evolved. The cellulose (sulfate) gave similar BPFC characteristics under air as under 1 atm O₂. Among the compounds the highest V_oc (open circuit voltage) value was 0.90 V for glutamic acid and phenylalanine.     

Microstructure and magnetic properties of aerosol‐deposited Sm‐Fe‐N thick films

In this study, the relationship among magnetic properties, Aerosol Deposition (AD) conditions, and microstructures in Sm‐Fe‐N AD films was investigated. The maximum thickness of 145µm was obtained under AD conditions of gas flow rate (gfr)=6liters/min for 10 min. The density of Sm‐Fe‐N films was in the range of 5.43 to 6.24g/cm³, that is, 71 to 81% of the X‐ray density of the Sm₂Fe₁₇N₃ compound reported (7.67g/cm³). The Sm‐Fe‐N AD films showed remanence in the range of 0.38 to 0.42 T, that is, 61 to 68% of that of the Sm‐Fe‐N host powder (0.62 T). The coercivities increased from 1.16 to between 1.74 and 1.79 T after the deposition because the grain size decreased from 1.94µm to 0.32µm. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(1): 8–13, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20214     

Direct deposition of nanostructured Pt particles onto a Ni foam from lyotropic liquid crystalline phase by displacement plating

Nanostructured Pt particles are directly deposited onto a Ni foam by utilizing displacement plating after a lyotropic liquid crystalline phase including Pt species was prepared within macropores of the Ni foam. The EDS mapping of Pt after deposition corresponds to the macroscopic framework of the Ni foam, indicating the uniform displacement plating of Pt on the surface of the Ni foam. The Pt particles of 150-250 nm in size are formed over the entire area of the surface of the Ni foam. The TEM images prove that the nanoscale rods (width: about 3 nm) are aggregated with each other to form nanoscale porosity. The active area of Pt can be estimated to be ca. 12 m²/g by using the cyclic voltammogram in sulfuric acid. Our method realizes one-step production of hierarchical macro-meso type porous electrodes.