Poly(vinyl pyrrolidone‐co‐vinyl acetate)‐graft‐poly(ε‐caprolactone) as a compatibilizer for cellulose acetate/poly(ε‐caprolactone) blends

Poly(vinyl pyrrolidone‐co‐vinyl acetate)‐graft‐poly(ε‐caprolactone) (PVPVAc‐g‐PCL) was synthesized by radical copolymerization of N‐vinyl‐2‐pyrrolidone (VP)/vinyl acetate (VAc) comonomer and PCL macromonomer containing a reactive 2‐hydroxyethyl methacrylate terminal. The graft copolymer was designed in order to improve the interfacial adhesiveness of an immiscible blend system composed of cellulose acetate/poly(ε‐caprolactone) (CA/PCL). Adequate selections of preparation conditions led to successful acquisition of a series of graft copolymer samples with different values of molecular weight ( ), number of grafts (n), and segmental molecular weight of PVPVAc between adjacent grafts (M_n (between grafts)). Differential scanning calorimetry measurements gave a still immiscible indication for all of the ternary blends of CA/PCL/PVPVAc‐g‐PCL (72 : 18 : 10 in weight) that were prepared by using any of the copolymer samples as a compatibilizer. However, the incorporation enabled the CA/PCL (4 : 1) blend to be easily melt‐molded to give a visually homogeneous film sheet. This compatibilizing effect was found to be drastically enhanced when PVPVAc‐g‐PCLs of higher and M_n (between grafts) and lower n were employed. Scanning electron microscopy revealed that a uniform dispersion of the respective ingredients in the ternary blends was attainable with an assurance of the mixing scale of several hundreds of nanometers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

On-chip transformation of bacteria

On-chip transformation of Escherichia coli cells was accomplished for the first time using a microbial array chip. The continuous E. coli transformation procedures were performed on a chip in which the microcompartment was composed of PDMS microfluidic channels and a silicon substrate predeposited with different plasmid DNAs. The PDMS microfluidic device enabled the parallel transformation of E. coli cells with various plasmid DNAs by separating each transformation area. The phenotypic differences reflecting different plasmid DNAs were identified by various approaches such as colorimetry, fluorometry, and electrochemical methods. This microbial array chip could become a versatile tool for many cell biological applications.     

An ultrasonic motor driven by the phase-velocity difference between two traveling waves

This paper presents a new ultrasonic motor in which the rotor rotation speed is locked by the phase-velocity difference between the two traveling waves propagating on the stator and the rotor. First, the unique construction to excite two traveling waves both in the stator and the rotor is described. Then, the operation principle of the present motor is revealed by our careful experiments. Dynamics of the two traveling waves are measured by an in-plane laser Doppler vibrometer under various conditions, as well as the motor performances. Our experiments show that the rotation speed of the motor is equal to the phase-velocity difference between the two traveling waves on the contact surfaces of rotor and stator. It is confirmed that the rotor rotates so as to cancel the phase-velocity difference between the traveling vibrations along the circumferences of the rotor and stator. If the load does not exceed the maximum torque that is determined by the vibration amplitude, the rotation speed is subject only to the phase-velocity difference.     

Oxygen saturation of skin reflects blood flow and stagnation

Skin is the largest organ of human body which can easily be observed non-invasively, but objective assessment of skin status is difficult. Therefore, we have focused on the oxygen saturation, and proposed the iterative optical path-length matrix method (OPLM) for estimating oxygen saturation of skin. Oxygen saturation of skin may help finding pre-disease state. In Kampo medicine (Japanese traditional herbal medicine), inspection of skin and tongue is one of the principal methods for diagnosis of the state. Kampo medicine contains a number of concepts which are useful for preventive medicine. The Oketsu status is a pathological concept in Kampo medicine, primarily denoting blood stasis/stagnation. In this study, we focused on oxygen saturation of skin as an objective index of skin properties, and studied correlation with the blood flow and the Oketsu score. First, we acquired Oketsu score of the patients, and measured oxygen saturation, hemoglobin concentration and blood flow of the patients at two locations: fingertip of the right first finger and dorsal surface of the right hand. Then, correlation among the values was calculated. As the result, the oxygen saturation showed large correlation with the blood flow and the Oketsu score at dorsal surface of hand. The oxygen saturation of skin will reflect systemic blood flow and Oketsu status, and it would help objective diagnosis by measuring skin color spectrum.     

AlN-to-Metal Direct Bonding Process Utilizing Sintering of Ag Nanoparticles Derived from the Reduction of Ag<Subscript>2</Subscript>O

Bonding between AlN and metals conventionally requires a surface modification process at high temperature such as metallization. The AlN-to-metal direct bonding process by sintering of Ag nanoparticles derived from in situ reduction of Ag₂O microparticles mixed with diethylene glycol is examined. Bonding was conducted at 300–500 °C after a preheating process at 100 °C, and the shear strength exceeded 20 MPa for the joint bonded at 500 °C. The role of preheating in the direct bonding of AlN and Ag was identified. The Ag nanoparticles generated during preheating at 100 °C cover the AlN surface, and they are converted into a thin Ag film. The thin film promotes the formation of a bonding layer, owing to the effective adhesion of the sintered Ag to the film, and contributes to the bonding of Ag and AlN. No interfacial reaction layer is observed. The same bonding process can be applied to other ceramics with poor wettability.     

Local structure investigations of accumulated damage in irradiated MgAl2O4

Damaged structures in the MgAl₂O₄ spinel induced by swift heavy ions were investigated using the X-ray absorption near edge structure (XANES) and small angle X-ray scattering (SAXS). Increasing the fluence of 100 MeV Xe ions leads to increased SAXS intensity and XANES spectral changes on both Mg and Al K-edges. The damaged regions of ion tracks were observed by SAXS to be cylindrical in shape with a diameter of 5 nm. The theoretical XANES spectra indicated that the changes in the experimental spectra were due to the cationic disordering between tetrahedral and octahedral sites. This disordering caused an increase in the inversion degree of the cations. Furthermore, the quantitative analysis of the XANES spectra revealed the preferential occupation of cations at the octahedral sites at high fluence.     

Balanced Secure Scan: Partial Scan Approach for Secret Information Protection

Scan-based Design-for-Testability technique is widely used to enhance the testability. However, it increases the vulnerability to attacks through scan chains for secure chips such as cryptographic circuits with embedded secret keys. This paper proposes a secure scan design method which protects the circuits containing secret information such as cryptographic circuits from scan-based side channel attacks. The proposed method prevents the leakage of secret information by partial scan design based on a balanced structure. We also guarantee the testability of both the design under test and DFT circuitry, and therefore, realize both security and testability. Experiments for RSA circuit shows the effectiveness of the proposed method.     

Solvent induced formation of an ordered nanorod array of gold/polymer composite by block copolymer film templating

We report a novel method to fabricate ordered arrays of gold-polymer composite nanorods with the orientation in the vertical direction using block copolymer (BCP) film. The salt precursor is selectively infiltrated within vertically aligned cylindrical domains of the BCP film by immersing the template in a simple aqueous solution of HAuCl(4). Scanning electron microscopy suggests that the salt might be uniformly positioned along the polymeric cylinders. A subsequent vacuum ultraviolet light irradiation simultaneously reduces the HAuCl(4) into spherical gold nanoparticles with mean diameter around 2?nm and removes the matrix of the BCP template to produce metal-polymer composite nanorods. While the solvent is methanol, the salt might be concentrated at the bottom of the BCP film. As a result, a periodic pattern of gold nanoparticles with average diameter around 11?nm is formed where the BCP film is completely etched away. The solvent can effectively tune the spatial distribution of the salt precursor along the polymeric cylinders, which is responsible for the different morphologies of the photochemically fabricated nanostructures.