Decomposition of environmentally persistent perfluorooctanoic acid in water by photochemical approaches

The decomposition of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water by UV-visible light irradiation, by H202 with UV-visible light irradiation, and by a tungstic heteropolyacid photocatalyst was examined to develop a technique to counteract stationary sources of PFOA. Direct photolysis proceeded slowly to produce CO2, F-, and short-chain perfluorocarboxylic acids. Compared to the direct photolysis, H2O2 was less effective in PFOA decomposition. On the other hand, the heteropolyacid photocatalyst led to efficient PFOA decomposition and the production of F- ions and CO2. The photocatalyst also suppressed the accumulation of short-chain perfluorocarboxylic acids in the reaction solution. PFOA in the concentrations of 0.34-3.35 mM, typical of those in wastewaters after an emulsifying process in fluoropolymer manufacture, was completely decomposed by the catalyst within 24 h of irradiation from a 200-W xenon-mercury lamp, with no accompanying catalyst degradation, permitting the catalyst to be reused in consecutive runs. Gas chromatography/mass spectrometry (GC/MS) measurements showed no trace of environmentally undesirable species such as CF4, which has a very high global-warming potential. When the (initial PFOA)/(initial catalyst) molar ratio was 10: 1, the turnover number for PFOA decomposition reached 4.33 over 24 h of irradiation.     

Location choice of multinational enterprises in China: Comparison between Japan and Taiwan

This paper explores the location choice of multinational enterprises (MNEs) in China, shedding special light on the role of agglomeration of same‐nationality firms. We examine how this role differs according to firms' productivity. Furthermore, we compare the location choice of Japanese and Taiwanese MNEs in China, taking into consideration that Taiwanese MNEs experience less uncertainty in investing in China due to Taiwan's linguistic and cultural advantages. When considering firms' productivity, we find that less productive Japanese firms prefer to locate close to larger same‐nationality agglomerations while there are no differences in location choices in the case of Taiwanese firms.     

High-efficiency single-cell entrapment and fluorescence in situ hybridization analysis using a poly(dimethylsiloxane) microfluidic device integrated with a black poly(ethylene terephthalate) micromesh

Here, we report a high-efficiency single-cell entrapment system with a poly(dimethylsiloxane) (PDMS) microfluidic device integrated with a micromesh, and its application to single-cell fluorescence in situ hybridization (FISH) analysis. A micromesh comprising of 10 x 10 microcavities was fabricated on a black poly(ethylene terephthalate) (PET) substrate by laser ablation. The cavity was approximately 2 microm in diameter. Mammalian cells were driven and trapped onto the microcavities by applying negative pressure. Trapped cells were uniformly arrayed on the micromesh, enabling high-throughput microscopic analysis. Furthermore, we developed a method of PDMS surface modification by using air plasma and the copolymer Pluronic F-127 to prevent nonspecific adsorption on the PDMS microchannel. This method decreased the nonspecific adsorption of cells onto the microchannel to less than 1%. When cells were introduced into the microfluidic device integrated with the black PET micromesh, approximately 70-80% of the introduced cells were successfully trapped. Moreover, for mRNA expression analysis, on-chip fluorescence in situ hybridization (e.g., membrane permeabilization, hybridization, washing) can be performed in a microfluidic assay on an integrated device. This microfluidic device has been employed for the detection of beta-actin mRNA expression in individual Raji cells. Differences in the levels of beta-actin mRNA expression were observed in serum-supplied or serum-starved cell populations.     

Large Boundary Magnetism and Superfluidity of Liquid 3He in Nanometer-sized Porous Alumina

Continuous-wave NMR measurements were performed for liquid ³He in porous alumina with nominal pore size of 20 nm in diameter, at temperatures down to 0.3 mK. The signal is composed of two contributions: from the liquid and from the boundary solid layer of ³He on the alumina’s surface. The latter shows a well-known ferromagnetic tendency and signal intensities can be fitted to a Curie-Weiss law in the high temperature region. The obtained Weiss temperatures are 0.18 and 0.50 mK at 7.5 and 28 bar, respectively. ⁴He coverage (4 monolayers) completely eliminates boundary signal between 7.5 bar and 32.5 bar. The residual liquid signal shows frequency shift and broadening below superfluid transition temperatures depending on liquid pressures. The obtained P-T phase diagram well resembles that of bulk liquid ³He in spite of the very narrow pore-size comparable to the coherence length of superfluid ³He.      

Self-assembled molecular nanowires of 6,13-Bis(methylthio)pentacene: growth, electrical properties, and applications

We demonstrate a comprehensive study of self-assembled molecular nanowire, including molecular design, one-dimensional crystal growth, resistivity measurement of individual wire, and application to a field-effect transistor. Appropriate molecular design and control of interfacial interactions lead to single crystalline wire growth with an extensive pi-stacking motif. Resistivity measurements of an individual molecular wire indicate that these structural features are advantageous for electrical transport. Finally, field-effect transistors with single- and double-wire channels were fabricated to give some indication of the potential application of the molecular wires.     

Formation of magnetite by bacteria and its application

Magnetic particles offer high technological potential since they can be conveniently collected with an external magnetic field. Magnetotactic bacteria synthesize bacterial magnetic particles (BacMPs) with well-controlled size and morphology. BacMPs are individually covered with thin organic membrane, which confers high and even dispersion in aqueous solutions compared with artificial magnetites, making them ideal biotechnological materials. Recent molecular studies including genome sequence, mutagenesis, gene expression and proteome analyses indicated a number of genes and proteins which play important roles for BacMP biomineralization. Some of the genes and proteins identified from these studies have allowed us to express functional proteins efficiently onto BacMPs, through genetic engineering, permitting the preservation of the protein activity, leading to a simple preparation of functional protein-magnetic particle complexes. They were applicable to high-sensitivity immunoassay, drug screening and cell separation. Furthermore, fully automated single nucleotide polymorphism discrimination and DNA recovery systems have been developed to use these functionalized BacMPs. The nano-sized fine magnetic particles offer vast potential in new nano-techniques.     

Barotolerance of Staphylococcus aureus is increased by incubation at below 0 degrees C prior to hydrostatic pressure treatment

The effect of preincubation under low temperatures on inactivation of Staphylococcus aureus IFO 13276 by hydrostatic pressure treatment (HPT) was investigated. Preincubation before HPT was carried out by submerging cell suspension in an ethylene glycol bath at temperatures from 30 to −20 °C for 15 min. After HPT at the same temperatures, survivors of incubated S. aureus was not significantly (P>0.05) influenced when preincubation took place at temperatures above 0 °C. Survivors of incubated S. aureus, however, were approximately two log cycles higher when preincubation took place at temperatures below 0 °C. This increase in barotolerance of S. aureus was not observed in the presence of 40 μg/ml of chloramphenicol.     

Distribution of the sulfite resistance gene SSU1-R and the variation in its promoter region in wine yeasts

The SSU1-R gene provides high sulfite resistance to the wine yeast Y9-16B. In this study, we examined the distribution of this gene in 61 wine yeasts and 4 laboratory yeasts. We also analyzed the number of repeats of a 76-bp promoter sequence and its relationship to sulfite resistance. We found that the SSU1-R gene was present in 31 of the 61 wine yeasts. Furthermore, we found that the number of repeats in the promoter region of SSU1-R varied from two to six. Using RsaI, which cuts only once in the repeat, we suggested that the repeats all consisted of the 76-bp sequence. Finally, we found that there was a complex relationship between the number of repeats and sulfite resistance.     

Emission and atmospheric transport of particulate PAHs in Northeast Asia

The emission, concentration levels, and transboundary transport of particulate polycyclic aromatic hydrocarbons (PAHs) in Northeast Asia were investigated using particulate PAH measurements, the newly developed emission inventory (Regional Emission inventory in ASia for Persistent Organic Pollutants version, REAS-POP), and the chemical transport model (Regional Air Quality Model ver2 for POPs version, RAQM2-POP). The simulated concentrations of the nine particulate PAHs agreed well with the measured concentrations, and the results firmly established the efficacy of REAS/RAQM2-POP. It was found that the PAH concentrations in Beijing (China, source region), which were emitted predominantly from domestic coal, domestic biofuel, and other transformations of coal (including coke production), were approximately 2 orders of magnitude greater than those monitored at Noto (Japan, leeward region). In Noto, the PAH concentrations showed seasonal variations; the PAH concentrations were high from winter to spring due to contributions from domestic coal, domestic biofuel, and other transformations of coal, and low in summer. In summer, these contribution were decrease, instead, other sources, such as the on-road mobile source, were relatively increased compared with those in winter. These seasonal variations were due to seasonal variations in emissions from China, as well as transboundary transport across the Asian continent associated with meteorological conditions.     

Rapid low‐temperature synthesis of tetragonal single‐phase Li7La3Zr2O12

The formation of Li₇La₃Zr₂O₁₂ (LLZ), a Li ion conducting oxide with a garnet‐type crystal structure, from a powder mixture of Li₂CO₃, La(OH)₃, and ZrO₂ was investigated, and two possible reaction pathways were identified. Based on the obtained results, LLZ was synthesized at low temperatures and short reaction times, using Li₂CO₃, La(OH)₃, and La₂Zr₂O₇ (instead of ZrO₂) as starting materials. According to the proposed method, single‐phase LLZ was obtained by heating the initial mixture to 800°C for 1 hour in air, which eliminated possible Li losses. The produced LLZ species exhibited a tetragonal crystal structure with the lattice parameters a=1.3189(3) nm and c=1.2694(1) nm, while their transmission electron microscopy images confirmed that LLZ formation occurred through the dissolution of La₂Zr₂O₇ and La(OH)₃ in a Li₂CO₃ melt followed by LLZ precipitation from solution.