Acceleration of nonylphenol and 4-tert-octylphenol degradation in sediment by Phragmites australis and associated rhizosphere bacteria

We investigated biodegradation of technical nonylphenol (tNP) in Phragmites australis rhizosphere sediment by conducting degradation experiments using sediments spiked with tNP. Accelerated tNP removal was observed in P. australis rhizosphere sediment, whereas tNP persisted in unvegetated sediment without plants and in autoclaved sediment with sterile plants, suggesting that the accelerated tNP removal resulted largely from tNP biodegradation by rhizosphere bacteria. Three bacterial strains, Stenotrophomonas sp. strain IT-1 and Sphingobium spp. strains IT-4 and IT-5, isolated from the rhizosphere were capable of utilizing tNP and 4-tert-octylphenol as a sole carbon source via type II ipso-substitution. Oxygen from P. australis roots, by creating highly oxygenated conditions in the sediment, stimulated cell growth and the tNP-degrading activity of the three strains. Moreover, organic compounds from P. australis roots functioned as carbon and energy sources for two strains, IT-4 and IT-5, supporting cell growth and tNP-degrading activity. Thus, P. australis roots elevated the cell growth and tNP-degrading activity of the three bacterial strains, leading to accelerated tNP removal. These results demonstrate that rhizoremediation of tNP-contaminated sediments using P. australis can be an effective strategy.     

N-doped anodic titania nanotube arrays for hydrogen production

Titanium dioxide (TiO₂) nanotube arrays are grown in a mixed electrolyte by anodizing process. The anodic nanotubes for N-doping were calcinated at 773 K in a tube furnace with a mixture of NH₃ and Ar gas. The photocatalytic activity of N-doped TiO₂ nanotubes was carried out in a water-splitting reaction under UV and visible light irradiation. Various characterization techniques (Scanning electron microscopy, X-ray diffractometry, X-ray photo-electron spectroscopy, etc.) are used to study the surface morphology, phase of structure, and binding energy.     

Optical Resolution Membranes from Polysulfones Bearing Alanine Derivatives as Chiral Selectors

Polysulfones bearing a derivative of alanyl residue employed as chiral selectors were prepared by polymer modification. The specific rotation ([α]_D) of the polysulfone with a derivative of D ‐alanyl residue (PSf‐Ac‐D ‐Ala) was determined to be 2.87 deg · cm² · g^?1 (c = 1.00 g · dL^?1 in DMF) and that with L ‐alanyl residue (PSf‐Ac‐L ‐Ala) to be ‐2.36 deg · cm² · g^?1 (c = 1.00 g · dL^?1 in DMF). The membrane from PSf‐Ac‐D ‐Ala preferentially adsorbed the D ‐isomer of Glu from racemic mixture of Glu and vice versa. Chiral separation ability was studied by applying a potential difference as a driving force for membrane transport. The permselectivity of PSf‐Ac‐D ‐Ala toward D ‐Glu (α_D/L) was determined to be 1.40, and that of PSf‐Ac‐L ‐Ala toward the L ‐isomer (α_L/D) to be 1.48 at 18.0 V, reflecting their adsorption selectivity.

     

A multimedia service composition scheme for ubiquitous networks

It is a challenging task to develop a high quality and secure multimedia service for mobile terminals used in the ubiquitous computing environment. One of the issues is the resource limitation of mobile terminals. In this paper, we presented a multimedia service composition scheme for sharing computer and communication resources by using plural terminals to compensate for this resource limitation. The proposed scheme is based on user authentication, service access control, and the multi-agent-based adaptive Quality-of-Service (QoS) control framework that we developed. We also proposed a novel access mode control based on the trustworthiness of users and extension of the multi-agent-based adaptive QoS control framework to plural users. Focusing on the home network as a typical ubiquitous network, we implemented a prototype testbed system and showed experimental results for the multimedia service composition.     

A study on cubic boron nitride (CBN) milling of hardened cast iron for productive and quality manufacturing of machine tool structural components

To improve efficiency and cost performance of cast iron machine tool component fabrication, an alternative process must be developed in order to replace the grinding process, which often causes a bottleneck in production. As an alternative manufacturing approach, this research applies cubic boron nitride (CBN) hard milling operations to eliminate the grinding process in order to improve the overall manufacturing process. A variety of hardened cast iron materials with Al and Mg additives and CBN tool types were prepared and tested based on a design of experimentation (DOE) to observe their effect on surface quality and tool life. Al and Mg were added to raw cast iron to achieve generation of oxide layers at the cutting edge during milling to protect the tool from wear. By executing the DOE, the optimal cutting conditions for achieving the best surface quality were introduced. Also, additional machinability tests were conducted with the optimal conditions in order to evaluate tool wear characteristics and surface quality of the machined workpieces. Based on the observation of the used tool by electron probe micro-analyzer (EPMA), a protective oxide layer of additives was observed at the cutting edge. Hardened cast iron with Al and Mg additives is found to show preferable wear and surface quality characteristics.     

Magnetite nanoparticles with high heating efficiencies for application in the hyperthermia of cancer

Magnetic hyperthermia is a safe method for cancer therapy. A gap-type alternating current magnetic field (100 kHz, 100–300 Oe) is expected to be clinically applicable for magnetic hyperthermia. In this study, magnetite nanoparticles (MNPs) varying in size from 8 to 413 nm were synthesized using a chemical coprecipitation and an oxidation precipitation method to find the optimum particle size that shows a high heating efficiency in an applied magnetic field. The particles' in vitro heating efficiency in an agar phantom at an MNP concentration of 58 mg Fe/ml was measured in an applied magnetic field. In a magnetic field of 120 Oe, the temperature increase (ΔT) of the agar phantom within 30 s was 9.3 °C for MNPs with a size of 8 nm, but was less for the other samples, while in a magnetic field of 300 Oe, ΔT = 55 °C for MNPs with a size of 24 nm, and ΔT = 25 °C for MNPs with a size of 8 nm. The excellent heating efficiency of MNPs with a size of 24 nm in a magnetic field of 300 Oe may be due to a combination of the effects of both relaxation and hysteresis losses of the magnetic particles. It is believed that MNPs with a size of 8–24 nm will be useful for the in situ hyperthermia treatment of cancer.     

Borate as a Phosphate Ester Mimic in Aldolase‐Catalyzed Reactions: Practical Synthesis of L‐Fructose and L‐Iminocyclitols

Dihydroxyacetone phosphate (DHAP)‐dependent aldolases have been widely used for the organic synthesis of unnatural sugars or derivatives. The practicality of using DHAP‐dependent aldolases is limited by their strict substrate specificity and the high cost and instability of DHAP. Here we report that the DHAP‐dependent aldolase L ‐rhamnulose 1‐phosphate aldolase (RhaD) accepts dihydroxyacetone (DHA) as a donor substrate in the presence of borate buffer, presumably by reversible in situ formation of DHA borate ester. The reaction appears to be irreversible, with the products thermodynamically trapped as borate complexes. We have applied this discovery to develop a practical one‐step synthesis of the non‐caloric sweetener L ‐fructose. L ‐Fructose was synthesized from racemic glyceraldehyde and DHA in the presence of RhaD and borate in 92 % yield on a gram scale. We also synthesized a series of L ‐iminocyclitols, which are potential glycosidase inhibitors, in only two steps.     

Individual and combined effects of water quality and empty bed contact time on As(V) removal by a fixed-bed iron oxide adsorber: Implication for silicate precoating

The individual and combined effects of changes in water quality (i.e. pH, initial concentrations of arsenate (As(V)) and competing ions) and empty bed contact time (EBCT) on As(V) removal performance of a fixed-bed adsorber (FBA) packed with a nanostructured goethite-based granular porous adsorbent were systematically studied under environmentally relevant conditions. Rapid small scale column tests (RSSCTs) were extensively conducted at different EBCTs with synthetic waters in which pH and the concentrations of competing ions (phosphate, silicate, and vanadate) were controlled. In the absence of the competing ions, the effects of initial As(V) concentration, pH, and EBCT on As(V) breakthrough curves were successfully predicted by the homogeneous surface diffusion model (HSDM) with adsorption isotherms predicted by the extended triple layer model (ETLM). The interference effects of silicate and phosphate on As(V) removal were strongly influenced by pH, their concentrations, and EBCT. In the presence of silicate (≤21 mg/L as Si), a longer EBCT surprisingly resulted in worse As(V) removal performance. We suggest this is because silicate, which normally exists at much higher concentration and moves more quickly through the bed than As(V), occupies or blocks adsorption sites on the media and interferes with later As(V) adsorption. Here, an alternative operating scheme of a FBA for As(V) removal is proposed to mitigate the silicate preloading. Silicate showed a strong competing effect to As(V) under the tested conditions. However, as the phosphate concentration increased, its interference effect dominated that of silicate. High phosphate concentration (>100 μg/L as P), as experienced in some regions, resulted in immediate As(V) breakthrough. In contrast to the observation in the presence of silicate, longer EBCT resulted in improved As(V) removal performance in the presence of phosphate. Vanadate was found to compete with As(V) as strongly as phosphate. This study reveals the competitive interactions of As(V) with the competing ions in actual adsorptive treatment systems and the dependence of optimal operation scheme and EBCT on water quality in seeking improved As(V) removal in a FBA.