An Advanced Effective Capacitance Model for Calculating Gate Delay Considering Input Waveform Effect

In deep submicron designs, predicting gate delay time is a noteworthy work for Static Timing Analysis. The effective capacitance Ceff concept is usually used to calculate the gate delay with interconnect loads. Conventionally, the input-signal to the gate is always assumed as a ramp waveform. However, the input signal is also the output of CMOS gates with interconnect loads and not the ramp waveform. Thus the simple assumption as a ramp signal results in significant influence on the delay calculation. In this paper, an advanced effective capacitance model is proposed to consider both the input waveform effect and the interconnect loads, where the nonlinear influence of input waveform is modeled as one part of the effective capacitance for calculating the gate delay. Experimental results show a significant improvement in accuracy when the input waveform effect is considered.     

Electrochemical oxidation of oxalic acid at highly boron-doped diamond electrodes

Electrochemical oxidation of oxalic acid has been investigated at bare, highly boron-doped diamond electrodes. Cyclic voltammetry and flow injection analysis with amperometric detection were used to study the electrochemical reaction. Hydrogen-terminated diamonds exhibited well-defined peaks of oxalic acid oxidation in a wide pH range. A good linear response was observed for a concentration range from 50 nM to 10 microM, with an estimated detection limit of approximately 0.5 nM (S/N = 3). In contrast, oxygen-terminated diamonds showed no response for oxalic acid oxidation inside the potential window, indicating that surface termination contributed highly to the control of the oxidation reaction. An investigation with glassy carbon electrodes was conducted to confirm the surface termination effect on oxalic acid oxidation. Although a hydrogen-terminated glassy carbon electrode showed an enhancement of signal-to-background ratio in comparison with untreated glassy carbon, less stability of the current responses was observed than that at hydrogen-terminated diamond.     

Formation of filamentous appendages by Acinetobacter sp. Tol 5 for adhering to solid surfaces

The toluene-degrading bacterium Acinetobacter sp. Tol 5 is highly adhesive to solid surfaces owing to two filamentous cell appendages, namely, anchors and peritrichate fibrils. When growing this bacterium in the presence of a carrier made of polyurethane foam, almost all the cells adhered to the surface of the carrier. In contrast, when Tol 5 cells were grown in the absence of the polyurethane carrier, the cells were suspended as aggregated cells or individually dispersed cells. The aggregated cells possessed the cell appendages and showed an adhesiveness similar to that of cells grown in the presence of the carrier, while the dispersed cells scarcely produced the cell appendages and showed a low level of adhesiveness. The dispersed cells started to adhere to the polyurethane carrier by producing the filamentous appendages within 30 min of the addition of the carrier as a substratum and toluene as a carbon source. Peritrichate fibrils just sprouting and growing anchors longer than 3 microm were observed when the cells started to adhere. This suggests that the presence of surface areas sufficient for adhesion might trigger cell appendage formation in Tol 5 cells for adhesion by increasing the amount of cell contact with the surfaces.     

Stabilization of affinity-tagged recombinant protein during/after its production in a cell-free system using wheat-germ extract

We found that the affinity tag fused to the carboxyl (C-) terminal of a single-chain Fv (scFv) antibody was proteolytically degraded in a wheat germ cell-free protein synthesis system. The addition of two extra residues of glycine to the tail of the cMyc tag significantly increased the stability of the tag, suggesting that wheat endogenous carboxypeptidase(s) play a primary role in the C-terminal tag-specific degradation. In addition to the modification of the tag sequence, addition of diisopropyl fluorophosphate, which is known as an inhibitor of carboxypeptidases, prevented the cMyc tag sequence degradation. The effects of other protease inhibitors on the translation reaction and stability of the synthesized protein are also reported.     

Direct electrochemical detection of sodium azide in physiological saline buffers using highly boron-doped diamond electrodes

Direct detection of sodium azide was examined by using highly boron-doped diamond (BDD) electrodes in some physiological saline buffer solutions. Three important saline buffers, ADA buffer (N-(2-acetamido) iminodiacetic acid), sodium EDTA and imidazole, were investigated. Hydrogen-terminated BDD was fixed for the investigation since it showed much better sensitivity for azide oxidation in comparison with the oxygen-terminated one. Wide range of buffer concentration was examined. A well-separated peak of sodium azide was observed in its mixture with the buffers, resulting in selective sodium azide detection. The current responses were exactly total addition of sodium azide and buffer current responses. The present method was evidenced to be available for direct detection of sodium azide in two samples of commercial diluents for cell counting. A standard addition method was applied. Sodium azide concentrations of 502 and 1355 μg mL⁻¹ were detected in both samples with the R.S.D.s of 0.07 and 2.37%, respectively. Validation was achieved by the comparison with the sample concentrations given by the manufacturer. Simple, selective, good sensitivity and excellent reproducible detection make the diamond electrodes very attractive for numerous electroanalytical applications.     

Photochromism induced magnetization changes in Prussian Blue ultrathin films fabricated into the Langmuir-Blodgett films composed of an amphiphilic azobenzene and a deoxyribonucleic acid

A photomagnetic ultrathin film consisting of an azobenzene, a deoxyribonucleic acid, and Prussian Blue has been fabricated by the Langmuir-Blodgett method. Prussian Blue layers in the films were a two-dimensional structure with the height of 50 Å and the average coherence length of 210 Å. Reversible photoisomerization of the azobenzenes was observed even in the films. The films exhibit the long-range ferromagnetic order below 4.2 K and moreover, upon photoillumination at 2 K, reversible changes in the magnetization were realized with the value of ca. 1.0%. This photoswitching in the magnetization is due to changes in the electrostatic field induced by photoisomerization.     

Optical material of high refractive index resin composed of sulfur‐containing aliphatic and alicyclic methacrylates

A resin having a high refractive index and a high Abbe number was produced by radical polymerization of a polymerizable monomer mixture composed of essentially sulfur‐containing aliphatic methacrylates or alicyclic methacrylates. We provide an optical material composed of said resin, specifically, a lens. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 45–49, 2000     

Bit duplication technique to generate hard quadratic unconstrained binary optimization problems with adjustable sizes

Quadratic unconstrained binary optimization (QUBO) is a combinatorial optimization to find an optimal binary solution vector that minimizes the energy value defined by a quadratic formula of binary variables in the vector. The main contribution of this article is to propose the bit duplication technique that can specify the number of duplicated bits, so that it can generate hard QUBO problem with adjustable sizes. The idea is to duplicate specified number of bits and then to give constraints so that the corresponding two bits take the same binary values. By this technique, any QUBO problem with $n$ bits is converted to a hard QUBO problem with $(m+n)$ bits . We use random QUBO problems, N-Queen problems, traveling salesman problem and maximum weight matching problems for experiments. The performance of QUBO solvers including Gurobi optimizer, Fixstars Amplify AE, OpenJij with SA, D-Wave samplers with SA, D-Wave hybrid and ABS2 QUBO solver are evaluated for solving these QUBO problems. The experimental results show that only a small scale of duplicated bits can make QUBO problems harder. Hence, the bit duplication technique is a potent method to generate hard QUBO problems and generated QUBO problems can be used as benchmark problems for evaluating the search performance of QUBO solvers.