Ammonia accumulation in culture broth by the novel nitrogen-fixing bacterium, Lysobacter sp. E4

This is the first report that Lysobacter fixes nitrogen under free-living conditions, as shown by its ability to grow on nitrogen-free medium and accumulate relatively high amounts of ammonia in the culture broth. Growth of the E4 Lysobacter strain, isolated in a screen for nitrogen-fixing and ammonia-producing bacteria, resulted in higher ammonia accumulation (0.53 mM ammonium ion concentration) in media containing glucose rather than other tested carbon sources. The optimum glucose concentration was 0.30% at an initial medium pH of 7.0 and incubation temperature of 30 °C. From time-course experiments, when the glucose in the culture was exhausted, ammonia began to be accumulated, and maximum ammonia accumulation (∼ 1.60 mM) was reached after 8 days of incubation. Ammonia accumulation by this strain required molybdenum, manganese, and iron.     

Development of fast-scanning laser probe system based on knife-edge method for diagnosis of RF surface acoustic wave devices

This paper describes the development of a high-speed laser probe system for surface acoustic wave (SAW) devices. A fast scanning rate of 2.5 kS/s is realized by continuous stage translation and successive acquisition of the detector output by a high-speed data-logger. Trigger pulses are generated from the output of a high-precision linear-scale installed in the translation stage and fed to the data-logger for the synchronization with the stage movement. The phase-sensitive, knife-edge method is used for the optical detection. This makes the system very unsusceptible to low-frequency mechanical vibration caused by the fast stage translation. The system is applied for the characterization of spurious resonance modes in SAW devices. In conjunction with skillful use of image processing in wavenumber domain, it is shown how the present system is effective in the diagnosis and development of SAW devices.     

Efficient estimation and particle filter for max‐stable processes

Extreme values are often correlated over time, for example, in a financial time series, and these values carry various risks. Max‐stable processes such as maxima of moving maxima (M3) processes have been recently considered in the literature to describe time‐dependent dynamics, which have been difficult to estimate. This article first proposes a feasible and efficient Bayesian estimation method for nonlinear and non‐Gaussian state space models based on these processes and describes a Markov chain Monte Carlo algorithm where the sampling efficiency is improved by the normal mixture sampler. Furthermore, a unique particle filter that adapts to extreme observations is proposed and shown to be highly accurate in comparison with other well‐known filters. Our proposed algorithms were applied to daily minima of high‐frequency stock return data, and a model comparison was conducted using marginal likelihoods to investigate the time‐dependent dynamics in extreme stock returns for financial risk management.     

Role of repetitive nine-residue sequence motifs in secretion, enzymatic activity, and protein conformation of a family I.3 lipase

A family I.3 lipase from Pseudomonas sp. MIS38 (PML) contains 12 repeats of a nine-residue sequence motif in the C-terminal region. To elucidate the role of these repetitive sequences, mutant proteins PML5, PML4, PML1, and PML0, in which 7, 8, 11, and all 12 of the repetitive sequences are deleted, and PMLdelta19, in which 19 C-terminal residues are truncated, were constructed. Escherichia coli DH5 cells carrying the Serratia marcescens Lip system permitted the secretion of the wild-type and all of the mutant proteins except for PMLdelta19, although they were partially accumulated in the cells in an insoluble form as well. Both the secretion level and cellular content of the proteins decreased in the order PML > PML5 > PML4 > PML1 > PML0, indicating that repetitive sequences are not required for secretion of PML but are important for its stability in the cells. All the mutant proteins were purified in a refolded form and their biochemical properties were characterized. CD spectra, the Ca2+ contents, and susceptibility to chymotryptic digestion strongly suggested that the five repetitive sequences remaining in PML5 are sufficient to form a beta-roll structure, whereas the four in PML4 are not. PML5 and PMLdelta19 showed both lipase and esterase activities, whereas PML4, PML1, and PML0 were inactive. These results suggest that the enzymatic activity of PML is not seriously affected by a deletion or truncation at the C-terminal region as long as a succession of repetitive sequences can build a beta-roll structure.     

Performance of nanofiber/microfiber hybrid air filter prepared by wet paper processing

High-performance air filters composed of a hybrid structure of nanofiber/microfiber were fabricated using wet paper processing. Two types of nanofibers (NF) with average diameters of 180 and 234?nm were mixed with a suspension of microfibers (11.5 and 11.7?µm) in various mixing fractions. Then, the suspension was filtered to fabricate hybridized fiber sheets with a known nanofiber/microfiber composition. The effects of NF diameter and mixing fraction on the performance of the hybrid filters were experimentally investigated. With increasing NF fraction, both the particle collection efficiency and the pressure drop increased. The quality factor (Q_f) was used to evaluate the performance of the prepared filters. As predicted by the single fiber filtration theory, the experimentally obtained Q_f was almost independent of the mixing fraction of the NF. The collection efficiency and pressure drop of the hybrid filters could be controlled by the NF fraction at the same Q_f. Moreover, the inhomogeneity factor of fiber packing (δ) did not significantly affect Q_f over the δ range from 3 to 23 for our filters. This implies that the lower particle capturing efficiency due to heterogeneous packing could be compensated by a decrease in the pressure drop, resulting in the same Q_f value. Therefore, Q_f for particles smaller than 100?nm, which are in the diffusion-controlled regime, can be increased by reducing the NF diameter.

Copyright © 2019 American Association for Aerosol Research     

High-Temperature Phase Transition of Y4Al2O9

Reversible thermal phase transition was observed for Y₄Al₂O₉ at 1377°C with a hysteresis width of 78°C using differential scanning calorimetry. The enthalpy of the transition (Δ H ) was about 300 cal/mol. Powder X-ray diffraction peaks of the high-temperature phase, as well as the peaks of the low-temperature phase, were characterized with a monoclinic unit cell. Thermal hysteresis was also confirmed by the temperature dependence of the lattice parameter. The unit cell volume of the high-temperature phase was 0.5% smaller than that of the low-temperature phase at 1400°C.     

A method for generating a standard magnetic field in a circularwaveguide

In order to minimize the effect of electromagnetic interference and the surrounding conductive materials in the calibration of small loop antennas used above HF frequencies, a novel method for generating a standard magnetic field in a circular waveguide is proposed. A method for obtaining the average magnetic-field strength incident on a receiving loop by placing the radiating and receiving circular loop antennas within a circular waveguide operated below the cutoff frequency region is described. The differences between the theoretical and experimental values of the field strength are within 0.1 dB between 10 and 150 MHz for the radiating and receiving loops with radii of 1.0 cm and within 0.15 dB between 10 and 110 MHz for radiating and receiving loops with a radii of 1.5 cm     

Growth and Characterization of Tl2Ba2CuOx(Tl-2201) Single Crystals

A new closed-atmosphere method using a gold crucible has been developed to grow single crystals of the Tl-based cuprate superconductors by a self-flux growth method. This new method can provide us mm-sized single crystals of Tl ₂ Ba ₂ CuO _x . It should be noted that the value in the resistivity ratio R(300K)/R(T _c ) (RRR) of one of the as-grown crystals is 18.3. This high RRR value indicates that the newly developed method is useful to obtain extremely high-quality single crystals of Tl ₂ Ba ₂ CuO _x .     

Design considerations on surface acoustic wave resonators with significant internal reflection in interdigital transducers

This paper discusses, both qualitatively and quantitatively, the operation and the design principle of current surface acoustic wave (SAW) resonators in which the internal reflection within interdigital transducers (IDTs) is not negligible and lower capacitance ratio is necessary. For the purpose, the p-matrix expression is used with the help of the coupling-of-modes theory. The internal reflection causes: deformation of the IDT passband shape, frequency dependence of the effective SAW velocity within IDTs, and suppression of higher-order resonances. It is shown that these features can be effectively used to enhance performances of both one-port SAW resonators and two-port double-mode SAW (DMS) filters. In addition, under proper designs accounting for the internal reflection, most of all structural discontinuities can be removed, and is most preferable for the reduced scattering loss at the discontinuity. Design criteria also are presented for DMS filters of wide bandwidth, and it is demonstrated how device performances are improved by proper design accounting for the criteria.     

A matched filter approximation for SC/MMSE iterative equalizers

This letter proposes a new iterative ISI equalization algorithm that offers low computational complexity: order L² with channel memory length L. The proposed algorithm is an extension of Reynolds and Wang's SC/MMSE (soft canceler followed by MMSE filter) equalizer: approximations are used properly to reduce the computational complexity. It is shown that the approximations used in the proposed algorithm do not cause any serious performance degradations from the trellis-based iterative equalization algorithms