A Temperature‐Controllable Microelectrode and Its Application to Protein Immobilization

This letter presents a smart integrated microfluidic device which can be applied to actively immobilize proteins on demand. The active component in the device is a temperature‐controllable microelectrode array with a smart polymer film, poly(N‐isopropylacrylamide) (PNIPAAm) which can be thermally switched between hydrophilic and hydrophobic states. It is integrated into a micro hot diaphragm having an integrated micro heater and temperature sensors on a 2‐micrometer‐thick silicon oxide/silicon nitride/silicon oxide (O/N/O) template. Only 36 mW is required to heat the large template area of 2 mm×16 mm to 40°C within 1 second. To relay the stimulus‐response activity to the microelectrode surface, the interface is modified with a smart polymer. For a model biomolecular affinity test, an anti‐6‐(2, 4‐dinitrophenyl) aminohexanoic acid (DNP) antibody protein immobilization on the microelectrodes is demonstrated by fluorescence patterns.     

Continuous generation of hydrogel beads and encapsulation of biological materials using a microfluidic droplet-merging channel

In this paper, we describe a method for encapsulation of biomaterials in hydrogel beads using a microfluidic droplet-merging channel. We devised a double T-junction in a microfluidic channel for alternate injection of aqueous fluids inside a droplet unit carried within immiscible oil. With this device, hydrogel beads with diameter <100 μm are produced, and various solutions containing cells, proteins and reagents for gelation could merge with the gel droplets with high efficiency in the broad range of flow rates. Mixing of reagents and reactions inside the hydrogel beads are continuously observed in a microchannel through a microscope. By enabling serial injection of each liquid with the dispersed gel droplets after they are produced from the oil-focusing channel, the device simplifies the sample preparation process, and gel-bead fabrication can be coupled with further assay continuously in a single channel. Instantaneous reactions of enzyme inside hydrogel and in-situ formation of cell-containing beads with high viability are demonstrated in this report.     

Liquid nucleating additives for improving thermal insulating properties and mechanical strength of polyisocyanurate foams

The effects of liquid-type nucleating silane additives on the cell structure, mechanical strength, and thermal insulating properties of the polyisocyanurate (PIR) foams have been studied. The PIR foams synthesized with hexamethyldisilazane (HMDS) as a silane additive showed the smaller average cell size and lower thermal conductivity than those of the PIR foams prepared with the hexamethyldisiloxane, dimethoxydimethylsilane, and hexadecyltrimethoxysilane. When HMDS was added, average cell size of the PIR foam was becoming smaller due to lower surface tension of the polyol solution, thereby the nucleation rate and number of bubbles produced were increased and then the cell size becomes smaller. The additives likely act as nucleating agents during the formation of PIR foams. The smaller cell size appears to be one of the major reasons for the improvement of thermal insulation properties and mechanical properties of the PIR foams. From the results of cell size, thermal conductivity, and mechanical strength of the PIR foams, it is suggested that the HMDS may be the efficient liquid-type additive for the reduction of cell size and improvement of the thermal insulation property of the PIR foams.     

Performance of NiB inhibitor for PbSCC of alloy 600 in Pb-contaminated water and caustic solutions

Nickel-based iron-chromium alloys are used as steam generator (SG) tubing materials in nuclear power plants (NPPs) but experience intergranular stress corrosion cracking (IGSCC) and lead stress corrosion cracking (PbSCC) due to the harsh operating conditions of NPPs. In order to improve the integrity of SGs, many studies have sought suitable inhibitors for IGSCC, while those for PbSCC have been sought to a limited extent. In this study, the performance of nickel boride (NiB) as an inhibitor for PbSCC was evaluated. Nickel boride has been shown to be a good inhibitor for IGSCC of Alloy (or Inconel) 600 in a caustic aqueous solution containing no lead (Pb). No significant SCC was observed to occur in Alloy 600 tested in pure water under the slow strain rate test (SSRT) condition in this study. A mixed mode of IGSCC and TGSCC, however, occurred relatively easily in Alloy 600 tested in pure water containing lead oxide (PbO) at 315 °C. The susceptibility of Alloy 600 to SCC decreased with the addition of NiB, implying that NiB can be used as an inhibitor for PbSCC in Pb-contaminated water.     

A digit-serial multiplier for finite field GF(2/sup m/)

In this paper, an efficient digit-serial systolic array is proposed for multiplication in finite field GF(2/sup m/) using the standard basis representation. From the least significant bit first multiplication algorithm, we obtain a new dependence graph and design an efficient digit-serial systolic multiplier. If input data come in continuously, the proposed array can produce multiplication results at a rate of one every /spl lceil/m/L/spl rceil/ clock cycles, where L is the selected digit size. Analysis shows that the computational delay time of the proposed architecture is significantly less than the previously proposed digit-serial systolic multiplier. Furthermore, since the new architecture has the features of regularity, modularity, and unidirectional data flow, it is well suited to VLSI implementation.     

Effect of steaming,freezing, and re-steaming on the texture properties of non-glutinous rice cakes

The effects of steaming time (6, 8, and 10 min), freezing storage period, and re-steaming for thawing on the textural properties of non-glutinous rice cakes (baekseolgi) were investigated. As the steaming time increased, the rice cakes softened. In particular, the sample that was steamed for 10 min showed lower hardness than those steamed for shorter periods. A short period of steaming was insufficient for water bound to the surface of the starch granules to penetrate the granules in the dough. During the re-steaming process of the frozen non-glutinous rice cake samples, the retrogradation of starch and water syneresis contributed to the increased hardness of non-glutinous rice cakes.     

Simplified stable crack growth analyses of welded CT specimens—comparison study of GE/EPRI, reference stress and R6 methods

This paper describes some simplified stable crack growth analyses of two kinds of inhomogeneous CT specimens. The one is machined from a submerged are welded plate of a nuclear pressure vessel A533B Class 1 steel, while the other is machined from an electron-beam welded plate of the A533B Class 1 steel and a high strength HT80 steel. In both specimens, initial cracks are placed to be normal to the fusion line. The ratio of yield stresses of the weld metal and the base metal of the A533B Class 1 steel is about 1·15, while that of the HT80 and the A533B Class 1 steels is about 1·4.

The generation phase crack growth analyses using the GE/EPRI and the reference stress methods are performed, calculating an applied load (P) and the J-value, while the application phase analyses of analyses using the R6 method are performed to calculate the maximum value of the applied load (P_max). Finally, some modification procedures of the three simplified estimation schemes are discussed in order to apply them to inhomogeneous material regimes.     

Ultra-High Capacity and Cyclability of β-phase Ca0.14V2O5 as a Promising Cathode in Calcium-Ion Batteries

Crystalline water-free β-phase Ca_0.14V₂O₅ is reported for the first time as a viable cathode material for calcium-ion batteries (CIBs). In contrast to layered α-V₂O₅ and δ-Ca_xV₂O₅·nH₂O, which have limited capacity, the β-phase delivers a reversible capacity of ≈247 mAh g⁻¹, which corresponds to the insertion/extraction of Ca²⁺ between Ca_0.14V₂O₅ and Ca_1.0V₂O₅. The process of Ca²⁺ insertion process and the accompanying structural relaxation are theoretically and experimentally verified. The initial insertion of Ca²⁺ into Ca_0.14V₂O₅ causes a slight shift of oxygen atoms surrounding hepta-coordination sites, creating penta-coordinated sites that are then partially filled up to Ca_0.33V₂O₅. Further insertion occurs through the stepwise occupation of up to 50% of neighboring hexa- and tetra-coordination sites to form Ca_0.67V₂O₅ and Ca_1.0V₂O₅, respectively. The rearrangement of oxygen atoms in Ca_0.14V₂O₅ also minimizes dimensional changes, leading to high cyclic stability during repeated charge/discharge cycles. The remarkable electrochemical performance of full cells containing a Ca_0.14V₂O₅ cathode and a K metal anode in Ca²⁺/K⁺ hybrid electrolytes, is also demonstrated, thanks to the inertness of K⁺ insertion into Ca_0.14V₂O₅ and the absence of calcium plating/stripping. The cyclic stability and high capacity of Ca_0.14V₂O₅ is not compromised in hybrid electrolytes, making it a viable CIB cathode.     

Ultrasensitive Strain Sensor Based on Separation of Overlapped Carbon Nanotubes

Although there have been remarkable improvements in stretchable strain sensors, the development of strain sensors with scalable fabrication techniques and which both high sensitivity and stretchability simultaneously is still challenging. In this work, a stretchable strain sensor based on overlapped carbon nanotube (CNT) bundles coupled with a silicone elastomer is presented. The strain sensor with overlapped CNTs is prepared by synthesizing line‐patterned vertically aligned CNT bundles and rolling and transferring them to the silicone elastomer. With the sliding and disconnection of the overlapped CNTs, the strain sensor performs excellently with a broad sensing range (≥145% strain), ultrahigh sensitivity (gauge factor of 42 300 at a strain of 125–145%), high repeatability, and durability. The performance of the sensor is also tunable by controlling the overlapped area of CNT bundles. Detailed mechanisms of the sensor and its applications in human motion detection are also further investigated. With the novel structure and mechanism, the sensor can detect a wide range of strains with high sensitivity, demonstrating the potential for numerous applications including wearable healthcare devices.