Identification and characterization of another 4-nitrophenol degradation gene cluster, nps, in Rhodococcus sp. strain PN1

4-Nitrophenol (4-NP) is a toxic compound formed in soil by the hydrolysis of organophosphorous pesticides, such as parathion. We previously reported the presence of the 4-NP degradation gene cluster (nphRA1A2) in Rhodococcus sp. strain PN1, which encodes a two-component 4-NP hydroxylase system that oxidizes 4-NP into 4-nitrocatechol. In the current study, another gene cluster (npsC and npsRA2A1B) encoding a similar 4-NP hydroxylase system was cloned from strain PN1. The enzymes from this 4-NP hydroxylase system (NpsA1 and NpsA2) were purified as histidine-tagged (His-) proteins and then characterized. His-NpsA2 showed NADH/FAD oxidoreductase activity, and His-NpsA1 showed 4-NP oxidizing activity in the presence of His-NpsA2. In the 4-NP oxidation using the reconstituted enzyme system (His-NpsA1 and His-NpsA2), hydroquinone (35% of 4-NP disappeared) and hydroxyquinol (59% of 4-NP disappeared) were detected in the presence of ascorbic acid as a reducing reagent, suggesting that, without the reducing reagent, 4-NP was converted into their oxidized forms, 1,4-benzoquinone and 2-hydroxy-1,4-benzoquinone. In addition, in the cell extract of recombinant Escherichia coli expressing npsB, a typical spectral change showing conversion of hydroxyquinol into maleylacetate was observed. These results indicate that this nps gene cluster, in addition to the nph gene cluster, is also involved in 4-NP degradation in strain PN1.     

Dependence of process characteristics on atomic-step density in catalyst-referred etching of 4H-SiC(0001) surface

Catalyst-referred etching (CARE) is a novel abrasive-free planarization method. CARE-processed 4H-SiC(0001) surfaces are extremely flat and undamaged over the whole wafer. They consist of single-bilayer-height atomic steps and atomically flat terraces. This suggests that the etching properties depend principally on the atomic-step density of the substrate surface. We used on-axis and 8 degrees off-axis substrates to investigate the processing characteristics that affect the atomic-step density of these substrates. We found a strong correlation between the removal rate and the atomic-step density of the two substrates. For the on-axis substrate, the removal rate increased with increasing surface roughness, which increases with an increasing atomic-step density. The removal rate ratio is approximately the same as the atomic-step density ratio of the two substrates.     

Characterization of terraces and steps on Cl-terminated Ge(111) surfaces after HCl treatment in N2 ambient

Germanium (Ge) is a promising substrate for semiconductor devices in the near future. However, wet-chemical preparations that enable the control of the structure of the Ge surface have not yet been developed. In this study, the surface structure of Ge(111) after HCl treatment is characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning tunneling microscopy (STM). XPS spectra revealed that purging with inert gas, such as nitrogen, is necessary to obtain a Ge surface free of oxide, probably because dissolved oxygen from air rapidly oxidizes the surface. Cl-terminated Ge surfaces are microscopically rough, but are composed of terraces and steps, as revealed by magnified STM images. Step edges run not along specific directions reflecting the crystallographic nature of the (111) surface but randomly. Many atomic-scale protrusions with the height of around 0.1 nm are dispersed on terraces. They are likely to be impurities such as carbon contaminants and water on Cl-terminated terraces attracted by Cl atoms with high electronegativity.     

Selective adsorption of organosilane molecules along step edges of atomically flattened Si(111) surfaces

We investigate the selective adsorption of organosilane molecules (3-aminopropyltriethoxysilane (APTES) and octadecyltrichlorosilane (OTS)) at the step edges of a flattened Si(111) surface by atomic force microscopy. The flattened Si(111) surface is formed by dipping a vicinal Si(111) wafer into ultralow-dissolved-oxygen water after treatment with HF. The selective adsorption of these organosilanes is achieved only when the Si(111) sample is pretreated with a Cu-containing solution to form Cu wires along the step edges of the Si(111) surface. This is probably due to the simultaneous formation of one-dimensional Si oxide covered with hydroxyl (OH) groups underneath Cu wires during the electroless reduction of Cu ions in water. At the step edges, APTES and OTS molecules are adsorbed as disperse clusters and as rows of bumps, respectively. The reason for this difference is still unclear, but a key factor is probably the control of the moisture content in the environment. The step edges, which are functionalized by organosilane molecules with various terminations such as -NH2 and -CH3, are expected to be utilized in novel nanoscale devices and processes.     

Efficient wet etching of GaN (0001) substrate with subsurface damage layer

Photoenhanced chemical (PEC) etching is applicable for processing an n-GaN (0001) surface rapidly. In this process, the surface oxidation is enhanced by photo-generated holes and the resulting oxide can dissolve into solutions. In current work, we conduct bias-assisted PEC etching in a KOH solution with a positively biased wafer, to remove the crystallographically highly damaged layer. The employed substrate was mechanically polished with diamond slurry of sub-micrometer particle size. Without the positive bias, the rate of PEC etching was quite low because the photogenerated holes were quickly depleted by the recombination process at the crystallographic defects and they could not contribute to the oxidation. On the other hand, in the case where the bias was applied, the photogenerated holes and electrons are separated forcibly in the band-bended surface, which effectively contributed to surface oxidation. As a result, a high removal rate was realized even on the damaged surface.     

Center of excellence for atomically controlled fabrication technology

This short review aims to show the introduction of the educational and research program of "Center of excellence of atomically controlled fabrication technology" supported ministry of education, culture, sports, science and technology--Japan. We would like to introduce research activity and a unique trait of educational system.     

Broadband near ultraviolet random lasing in ZnO 3-D nanowalls

Broadband near ultraviolet (NUV) random laser was achieved by Au nanoparticle loaded ZnO 3-D nanowalls. Au nanoparticle was loaded on ZnO 3-D nanowalls by photo-chemical deposition method using ionic liquid. The optical confinement by the 3-D nanowalls and enhancement of incident light scattering by Au nanoparticle increase the number of resonant modes, and thus leading to a broadband multiple spectrum random lasing. The results demonstrate an important step towards to expand the application scope of NUV laser on medical imaging of cells, solid-state lighting and optical sensor.     

A Real-time Scalable Object Detection System using Low-power HOG Accelerator VLSI

As described in this paper, a real-time object detection system using a Histogram of Oriented Gradients (HOG) feature extraction accelerator VLSI is presented. The VLSI [1, 2] enables the system to achieve real-time performance and scalability for multiple object detection under limited power condition. The VLSI employs three techniques: a VLSI-oriented HOG algorithm with early classification in Support Vector Machine (SVM) classification, a dual-core architecture for parallel feature extraction, and a detection-window-size scalable architecture with a reconfigurable MAC array for processing objects of different shapes. The test chip was fabricated using 65 nm CMOS technology. The measurement result shows that the VLSI consumes 43 mW at 42.9 MHz and 1.1 V to process HDTV (1920?×?1080 pixels) at 30 frames per second (fps). A multiple object detection system and a multiple scale object detection system are presented to demonstrate the system flexibility and scalability realized by VLSI and applicability for versatile application of object detection. On the multiple object detection system, a real-time object detection for HDTV resolution video is achieved with 84 mW of power consumption on a task to detect 2 types of targets while keeping comparable detection accuracy as software-based system. On the multiple scale object detection system, a task to detect 5 scales of a target is accomplished using a single VLSI. The power consumption of the VLSI is estimated to 102 mW on the task.     

Fatty Acid Conjugates of Water‐Soluble (±)‐trans‐Selenolane‐3,4‐diol: Effects of Alkyl Chain Length on the Antioxidant Capacity

Fatty acid monoesters of the title compound (DHS^red), of variable carbon chain length (propionate, laurate, myristate, palmitate, and stearate), were synthesized, and their antioxidant capacities were evaluated by means of a lipid peroxidation assay with lecithin/cholesterol liposomes. The selenides with long alkyl chains exhibited significant antioxidant activity (IC₅₀=9–34 μM ) against accumulation of lipid hydroperoxide. Incorporation of the myristate into the liposome was ≈50 % by EPMA analysis. Intermediacy of the selenoxide was examined by NMR. In addition, enhancement of interfacial redox catalytic activity was observed for the myristate, but not for PhSeSePh and edaravone, in a PhCl/H₂O biphasic peroxidation assay. These results suggested that a combination of a hydrophilic selenide moiety as a redox center with a long alkyl chain is an effective approach to selenium antioxidants with interfacial glutathione‐peroxidase‐like (GPx‐like) activity. The activity can be controlled by the alkyl chain length.     

Semantics for a Quantum Programming Language by Operator Algebras

This paper presents a novel semantics for a quantum programming language by operator algebras, which are known to give a formulation for quantum theory that is alternative to the one by Hilbert spaces. We show that the opposite of the category of W*-algebras and normal completely positive subunital maps is an elementary quantum flow chart category in the sense of Selinger. As a consequence, it gives a denotational semantics for Selinger’s first-order functional quantum programming language. The use of operator algebras allows us to accommodate infinite structures and to handle classical and quantum computations in a unified way.