Comparison of aerobic denitrifying activity among three cultural species with various carbon sources.

Abilities of three aerobic denitrifiers such as Alcaligenes faecalis, Microvirgula aerodenitrificans and Paracoccus pantotrophus were compared from the viewpoints of nitrate removal efficiency and organic matter utilization. First, the effect of carbon source was investigated. Although nitrate reduction was observed in all strains under aerobic conditions, a change of carbon source considerably affected the denitrification ability. In the case of P. pantotrophus, nitrate and nitrite were completely removed in three days under sodium acetate or leucine as a carbon source. In the case of A. faecalis, sufficient nitrate removal was observed only when sodium acetate or ethanol was added. P. pantotrophus and A. faecalis showed a higher ability of nitrate removal than that of M. aerodenitrificans. Therefore, P. pantotrophus was selected in order to investigate the effects of concentration and repetitive addition of carbon. Sodium acetate was used as a sole carbon source. Nitrate was not reduced when the carbon concentration was below 500 mgC/L. However, when carbon source was added repeatedly, nitrate was reduced under 100 mgC/L after the optical density of the bacterium reached above 1.0. This result indicated that a high enough level of bacterial density was necessary to express aerobic denitrification activity.     

Changes in enzyme activities at the pyruvate node in glutamate-overproducing Corynebacterium glutamicum

Glutamate is industrially produced by fermentation using Corynebacterium glutamicum. The key factor for efficient glutamate production by this microorganism has been considered to be a metabolic change at the 2-oxoglutarate dehydrogenase (ODH) branch point caused by a decrease in ODH activity under glutamate-overproducing conditions. However, this change would be insufficient because the ODH branch is merely the final branch in the glutamate biosynthetic pathway, and efficient glutamate production requires a balanced supply of acetyl-CoA and oxaloacetate (OAA), which are condensed to form a precursor of glutamate, namely, citrate. Therefore, there must be another (other) change(s) in metabolic flux. In this study, we demonstrated that a decrease in pyruvate dehydrogenase (PDH) activity catalyzes the conversion of pyruvate to acetyl-CoA. It is speculated that carbon flux from pyruvate to acetyl-CoA decreases under glutamate-overproducing conditions. Furthermore, an increase in pyruvate carboxylase (PC) activity, which catalyzes the reaction of pyruvate to OAA, is evident under glutamate-overproducing conditions, except under biotin-limited condition, which may lead to an increase in carbon flux from pyruvate to OAA. These data suggest that a novel metabolic change occurs at the pyruvate node, leading to a high yield of glutamate through adequate partitioning of the carbon flux.     

On Resource Arc for Petri Net Modelling of Complex Resource Sharing System

PFS-R – Production Flow Schema with Resources – is a novel graphical representation for complex resource sharing discrete production systems proposed in this paper. The PFS-R is an augmented version of the PFS (Production Flow Schema, previously proposed by the authors) which includes correspondences of system resources at each production step. The PFS-R is able to model system structures as well as system behaviours in a more simplified and transparent manner than ordinary Petri net representations. That is, the PFS-R solves an important drawback when actually adopting Petri nets as a design technique for intelligent manufacturing systems. First, the paper introduces the basic elements of PFS-R, and the equivalent transformations of PFS-R model into hybrid nets and Petri nets, taking into account the net conservativeness. Next, examples of discrete production systems to illustrate the effectiveness of PFS-R are presented. In addition, it is shown, using an example, that the correspondence between resources and production steps in the process flow has a tree structure, which is an effective way to evaluate whether or not the objects designed have a well-defined structure.     

Development of a pumping laser system for x-ray laser research

A two-beam chirped-pulse-amplification Nd:glass laser system dedicated to x-ray laser research is described. Each beam provides an output energy of 20 J with a typical pulse duration of 1.3 ps. A prepulse of variable duration is generated by use of a novel, to our knowledge, optical system. A reflection optical system, comprised of an off-axis parabolic mirror and a spherical mirror, produces a line focus with 6-mm length and 165-microm width without chromatic aberration. By use of this pumping laser system, the nickel-like silver x-ray laser at a wavelength of 13.9 nm has been demonstrated.     

Direct evidence of advantage of Cu(111) for graphene synthesis by using Raman mapping and electron backscatter diffraction

The advantageous crystallographic orientation of Cu surface for graphene synthesis by using thermal chemical vapor deposition (CVD) is examined by Raman mapping and electron backscatter diffraction. It is found that Cu(111) predominates over (110) and (100) for single- (SLG) or few-layer graphene (FLG) growth. To confirm this result we attempt the synthesis of graphene on Cu(111) single crystal film surfaces. We confirmed the formation of high quality and high uniformity SLG or FLG over more than 97% of the substrate surface area of 10 mm × 10 mm by Raman mapping.     

Catheter type thermal flow sensor with small footprint for measuring breathing function

Microsystem Technologies - We preivously developed a catheter type flow sensor for measuring breathing and heartbeat information from breathing at the mouth [Hasegawa et al. J Micromech Microeng...     

Anomalous phenomena in pressure drops of water flows through micro-orifices

Pressure drops were measured for high-velocity water flows through micro-orifices of various diameters. The observed pressure drop values agreed well with the values predicted by the Navier–Stokes equation for 400 and 100 μm diameter orifices, but were lower than the predicted values for orifices less than 50 μm in diameter. In particular, the measured pressure drop value was almost two orders of magnitude lower than the predicted value for the 10 and 5 μm diameter orifices. Several factors that may cause a reduction in pressure drop were considered, including orifice shape and deformation of the orifice foil, but none proved to be significant enough to cause such a large reduction. Elastic stress in orifice flow appeared to be the most plausible cause of the pressure drop reduction. The elastic stress, which was estimated by the jet thrust method, was found to be dependent on the mean velocity passing through the micro-orifices, which strongly supported the elasticity of water flows.     

Locating congested segments over the Internet by clustering the delay performance of multiple paths

Delay variation-based detection and location of congestion in a large network is considered. Since the Internet is still highly prone to performance deterioration due to transient large delays, locating a part of the network (segments) responsible is vital to ensure that Internet Service Providers can mitigate or prevent such performance deterioration. In the proposed method, the end-to-end packet delays from multiple origins to multiple destinations are actively and continuously measured. By analyzing those data on delay variation along each monitored path, congestion is detected by finding a delay performance deterioration worse than a predefined criteria and a congested segment responsible could be inferred by finding a set of paths among which delay variations are strongly correlated. This is a network tomographic approach based on a clustering technique that effectively tackles the correlation among packet delay variation along individual paths. The proposed method was evaluated through a real-world long-term experiment on the Japan’s commercial Internet, and was shown to have considerable potential to promptly locate congested segments through various analyses on the experimental results.     

Synthesis of MoSi2-TiSi2 pseudobinary alloys by reactive sintering

MoSi₂-TiSi₂ pseudobinary alloys are synthesized from mixtures of elemental powders of molybdenum, silicon, and titanium by reactive sintering under a pseudoisostatic pressure of 150 MPa. When the titanium content in the alloy increases from 0 to 33 at. pct, the density of the alloy decreases from approximately 6 to 4 g/cm³, while the relative density is more than 95 pct independent of the titanium content. Vickers hardness of the alloy is approximately 800 when the alloy consists of a monophase structure of α-MoSi₂ or β-MoSi₂. However, the hardness increases to approximately 950 when the alloy consists of a dual-phase structure of (α-MoSi₂+β-MoSi₂) or (β-MoSi₂+γ-TiSi₂). The oxidation resistance of the alloy at 773 K is approximately tripled when the titanium content increases from 0 to 1.7 at. pct, but the effect of the titanium content on the oxidation resistance becomes less remarkable as the titanium content increases.     

Use of quantum rods for display applications

We examined the use of quantum rods (QRs) in two configurations for display applications, including the backlight and emissive color pixels for liquid crystal and organic light‐emitting diode displays, respectively. For the backlight, we used an electrospun nanofiber sheet embedded with QRs, and found the nanofiber‐aligned sheet showed polarized emission with a very high outcoupling efficiency. We then fabricated emissive color pixels with QRs using an inkjet printer, and evaluated their optical properties. The color gamut area size was 82% of the BT2020 standard and the overlap with it was 69%.