On a posteriori estimates of inverse operators for linear parabolic initial-boundary value problems

We present numerically verified a posteriori estimates of the norms of inverse operators for linear parabolic differential equations. In case that the corresponding elliptic operator is not coercive, existing methods for a priori estimates of the inverse operators are not accurate and, usually, exponentially increase in time variable. We propose a new technique for obtaining the estimates of the inverse operator by using the finite dimensional approximation and error estimates. It enables us to obtain very sharp bounds compared with a priori estimates. We will give some numerical examples which confirm the actual effectiveness of our method.     

The effect of salinity on nitrite accumulation in a down‐flow hanging sponge reactor

BACKGROUND: In this study, the inductive effect of salinity on nitrite accumulation in a down‐flow hanging sponge (DHS) reactor, developed as a novel and cost‐effective wastewater treatment process, was evaluated by conducting a long‐term continuous experiment lasting more than 1400 days. RESULTS: The influent salinity was controlled by adding NaCl at concentrations ranging from 0 to 25 g Cl^? L^?1. The effluent nitrite increased with increases in salinity, i.e. the fraction of nitrite to total nitrogen in the effluent increased from 1.6% at 0 g Cl^? L^?1 to 87.6% at 25 g Cl^? L^?1. Fluorescence in situ hybridization (FISH) analysis revealed that as salinity increased, the nitrifying bacterial community in the DHS changed markedly at the species level. In particular, the dominant nitrite‐oxidizing bacteria changed from Nitrospira‐sublineage I at 0 g Cl^? L^?1 to Nitrobacter spp. at 15 g Cl^? L^?1. At 25 g Cl^? L^?1, no nitrite‐oxidizing bacteria were detected. CONCLUSION: Our findings suggest that the DHS reactor is suitable for cost‐effective nitrite production processes and that salinity control using NaCl is an effective method for inducing nitrite accumulation. Copyright © 2012 Society of Chemical Industry     

The inactive form of a yeast casein kinase I suppresses the secretory defect of the sec12 mutant. Implication of negative regulation by the Hrr25 kinase in the vesicle budding from the endoplasmic reticulum

Sec12p is the guanine nucleotide exchange factor of Sar1 GTPase and functions at the very upstream in the vesicle budding reactions from the endoplasmic reticulum (ER). We previously identified three yeast loci, RST1, RST2, and RST3, whose mutations suppressed the temperature-sensitive growth of the sec12-4 mutant (Nakano, A. (1996) J. Biochem. (Tokyo) 120, 642-646). In the present study, we cloned the wild-type RST2 gene by complementation of the cold-sensitive phenotype of the rst2-1 mutant. RST2 turned out to be identical to HRR25, a gene encoding a dual-specificity casein kinase I in yeast. The rst2-1 mutation, which is now renamed hrr25-2, was due to the T176I amino acid replacement in the kinase domain. This mutation remedied not only the temperature-sensitive growth but also the defect of ER-to-Golgi protein transport of sec12. Immunoprecipitation of the hemagglutinin-tagged Hrr25-2 protein and a subsequent protein kinase assay showed that the kinase activity of the mutant protein was markedly reduced. The overproduction of another kinase-minus mutant of Hrr25p (Hrr25p K38A) slightly suppressed the growth defect of sec12-4 as well. These observations suggest that the reduction of the kinase activity in the mutant protein is important for the suppression of sec12. We propose that Hrr25p negatively regulates the vesicle budding from the ER.     

A 2.5-GFLOPS, 6.5 million polygons per second, four-way VLIWgeometry processor with SIMD instructions and a software bypassmechanism

A four-way very long instruction word (VLIW), 312-MHz geometry processor with peripheral component interconnect/accelerated graphic port bus bridge was implemented in a 0.21-μm, 2.5-V, three-layer-metal CMOS process. We adopted (1) a software bypass mechanism, (2) single-instruction multiple-data stream instructions, (3) four sets of floating-point multiply add and accumulate execution units, (4) special condition code registers and a branch condition generator for a clipping operation, and (5) automatic clock delay tuning methodology. As a result of these features, we achieved a performance of 2.5 GFLOPS and 6.5 million polygons per second for a three-dimensional geometry processor, which is the highest published performance as a single geometry processor. The processor is applicable to computer-aided-design systems that require very high graphics performance     

A new method of accurate polarization measurement on isobaric analog resonance to detect parity non-conservation effect

For the study of parity mixing in the compound states, a method to measure the longitudinal analyzing power A_z of the isobaric analog resonance (IAR) as a function of energy in the proton elastic scattering is discussed. A thick target is used and energy loss of the protons in the target is utilized to measure the energy dependence. The energy resolution is presented and the sources of the systematic errors in A_z are discussed together with the way of their elimination. The method has been shown to be quite efficient for deriving both the transverse and the longitudinal analyzing powers. The measurement of A_z for the s-wave IAR at E_cm=5.86 MeV in ⁹⁰Zr(p,p) and the analysis to derive PNC matrix elements are described.     

Improvement of anode oxidation reaction of a fuel cell using ammonium formate with Pt‐Ir catalysis

We have attempted to develop high‐performance and safe fuel cells by using ammonium formate as a solid (powder) fuel. This solid fuel has the potential of safer transportability than liquid fuels such as methanol from the viewpoint of toxicity and flammability. In order to make use of some of the advantages of ammonium formate, we investigated the oxidation characteristics of ammonium formate with respect to a Pt electrode. Cyclic voltammograms indicate that ammonium formate has high oxidation activity with respect to a Pt electrode. We have also found that the oxidation of ammonium formate can be improved by the addition of Ir to Pt catalysts. It is highly likely that ammonium formate will be useful as a solid (powder) fuel for polymer electrolyte membrane (PEM) fuel cells. This new fuel will promote the development of safe fuel cells for PEM. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(4): 45–50, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21043     

Effects of mechanical force on crystalline structure of electrospun poly(1‐butene) membranes

Fibrous poly(1‐butene) membranes were prepared from solutions using mixed solvents via electrospinning. The electrospun fibrous poly(1‐butene) membranes were stretched at elongations of 8, 16 and 24%, respectively. Scanning electron microscopy and stress–strain analysis showed that the deformation was elastic at an elongation of 8%, while plastic deformation occurred above 16%. The crystalline transformation induced by mechanical stretching was investigated using wide‐angle X‐ray diffraction. The poly(1‐butene) membrane stretched at 24% exhibited decreased diffraction intensity at 2θ = 11.8° and 18.3°, corresponding to the (200) and (213) crystalline reflections, indicating that crystalline transformation from metastable form II to either stable form I or I′ occurred due to mechanical stretching. Copyright © 2011 Society of Chemical Industry     

Efficient synthesis and magnetic properties of triphenylamine bearing three nitronylnitroxide radicals

Improved synthesis and reinvestigation of the magnetic properties of triphenylamine bearing three nitronylnitroxide radicals (1) were carried out. Single crystal X-ray crystallographic analysis of 1 established that its molecular shape had a C₃-symmetry. Our newly prepared 1 showed different physical properties from those of reported. SQUID measurements of 1 showed that each of the three spins of 1 behaved independently at room temperature. In contrast, the three spins coupled antiferromagnetically at lower temperature as low as ca. 1.8 K. These spin behaviors can be explained by a regular triangular antiferromagnetic model (J/k_B = ?3.3 K) and interpreted as a spin frustration system.     

Dependence of off-leakage current on channel film quality in poly-Si thin-film transistors and analysis using device simulation

The dependence of off-leakage current on channel film quality in poly-Si thin-film transistors has been analyzed using two-dimensional device simulation. It is found that the off-leakage current decreases as the intragrain trap density decreases for the low V_gs. This is because the Phonon-assisted tunneling with Poole-Frenkel effect is the dominant mechanism of the carrier generation and the generation rate of carrier pair decreases as the intragrain trap density decreases. On the other hand, the off-leakage current slightly increases as the intragrain trap density decreases for the high V_gs. This is because the band-to-band tunneling is the dominant mechanism and the influence of the intragrain trap density to the carrier conductance is larger than that to the generation rate.