Oxidation of Methyl Linoleate in Oil-in-Water Micro- and Nanoemulsion Systems

Oxidation of methyl linoleate in O/W emulsions having droplets of median diameters ranging from 17 nm to 8.0 μm was carried out at 40°C. The oxidation process was analyzed on the basis of a kinetic equation of the autocatalytic type. The induction period was found to be shorter and the oxidation rate constant lower for emulsions with smaller oil droplets. The stoichiometry between methyl linoleate and oxygen was observed to be independent of both the size of oil droplet and the type of the surfactant and was found to be unity during the early stage of the oxidation. However, more oxgen was consumed in the oxidation of the methyl linoleate in the later half of the oxidation process.     

The effect of mannitol upon cochlear dysfunction induced by transient local anoxia

Transient local anoxia of the cochlea was induced by pressing the labyrinthine artery, and compound action potential (CAP) or endocochlear potential (EP) was measured before and after transient local anoxia ranging from 5 to 60 min using 106 albino guinea pigs. The complete interruption of the cochlear blood flow by this procedure and its full restoration after releasing the pressure on the artery was confirmed by a laser-Doppler flowmeter. The anoxia of less than 10 min induced no post-anoxic cochlear dysfunction, whereas the anoxia of a longer duration induced an irreversible dysfunction of the cochlea. It was evident that the post-anoxic recovery of the CAP threshold was worse as the anoxia period was prolonged, and CAP was almost completely abolished after 60-min anoxia. In animals which were administered mannitol intravenously just after the restoration of the cochlear blood circulation, the recovery of the CAP threshold was significantly better than that in the control animals, when the animals were subjected to local anoxia of 15- to 30-min duration. No beneficial effect, however, was observed in the 60-min anoxia group. In conclusion, local anoxia of 10 min or longer caused cochlear dysfunction, which was partially but significantly alleviated by mannitol.     

Oxidative stress-dependent inhibition of yeast cell growth by farnesylamine and its possible relation to amine oxidase in the mitochondrial fraction

Among various analogs of the isoprenoid farnesol (FOH), farnesylamine (FNH2) inhibited the growth of the budding yeast Saccharomyces cerevisiae by accelerating cellular reactive oxygen species (ROS) generation. Unlike the case with FOH, however, FNH2 did not cause mitochondrial transmembrane potential (mtDeltaPsi) hyperpolarization so that FNH2-treated cells were not protected against ROS production by inhibiting the proton pumping function of mitochondrial F(O)F1-ATPase. FNH2 promoted ROS generation even in cells of a respiration-deficient mutant, indicating a yeast metabolic pathway other than mitochondrial electron transport as the origin of ROS. FNH2 oxidase activity was detected in the yeast mitochondrial fraction, which produces hydrogen peroxide (H2O2) in the reaction with either FNH2 or geranylgeranylamine (GGNH2), in addition to polyamine oxidase activity specific for spermine. GGNH2 also exhibited the growth inhibitory effect with the accompanying induction of ROS generation, while such an activity was not detected with any of the polyamines tested or geranylamine. FNH2 oxidase, which was sensitive to a typical copper-chelating agent, diethyldithiocarbamic acid (DDC), could be solubilized with Triton X-100, and detected as a single band upon activity staining with FNH2 but not with spermine in polyacrylamide gel electrophoresis. FNH2-treated cells were partly protected against ROS production by the additional supplementation of DDC in the medium. Our results suggest the involvement of H2O2 production due to direct oxidation of FNH2 by copper amine oxidase in oxidative stress-dependent inhibition of yeast cell growth.     

Process Simulation and Economic Feasibility Analysis for a Hydrogen‐Based Novel Suspension Ironmaking Technology

A novel gas‐solid suspension ironmaking process is under development at the University of Utah, which would greatly reduce energy consumption and carbon dioxide emission compared with current blast furnace technology. The proposed process is based on the flash reduction of iron ore concentrate using a gaseous reagent, such as hydrogen, syngas, natural gas or a combination of thereof. A process flow sheet of the proposed ironmaking process using purchased hydrogen was constructed and then simulations were performed at several potential operating conditions. Ironmaking was simulated using two different process configurations. The simulation results show that the required fresh hydrogen would increase with higher excess driving force and operating temperature, but not greatly when hydrogen is preheated. Compared with the average blast furnace process, the proposed process would reduce energy consumption by 57 ‐ 60%, using the higher heating value of hydrogen (71 – 73%, if the lower heating value is used), when hydrogen and coal are considered as the starting materials in the respective processes. The economic feasibility analysis using net present value (NPV) indicates that the proposed process could be economically feasible at elevated hot metal prices and/or if reduction in carbon dioxide emissions has a significant value in a cap and trade scenario.     

On-site measurement of trace-level sulfide in natural waters by vapor generation and microchannel collection

Aqueous sulfide plays an important role in the environment even at low concentrations. However, it is unstable, which means field samples cannot be transported to the laboratory for analysis without fixation. In this work, a novel method was developed to determine trace levels of sulfide on site. This method is based on vapor generation and collection in a special microchannel device followed by fluorescence measurement (VG-μGAS). The microchannel scrubber gave a high enrichment factor, and a high sensitivity was achieved, which allowed measurement of nanomolar (nM) levels of sulfide. The theoretical approach to vapor generation for several compounds is discussed to evaluate the applicability of the method to these analytes, and compounds having a low Henry's law constant (<1 M atm(-1)) are suitable to measure by VG-μGAS. Under optimized conditions, concentrations of 1.0-100 nM of sulfide could be measured. The sulfide contents of hot spring, aquarium, pond, and seawater were successfully measured by this method. Nanomolar levels of sulfide could be measured on site without loss of analyte, and results were obtained instantly in the field, both of which are advantageous for effective field surveys. The method was also applied to field measurements of aqueous sulfide in the Ariake Sea and Lake Baikal.     

Analysis of spinosad in animal and fishery products by LC-MS

We investigated the determination of spinosyn A and spinosyn D, the active ingredients of spinosad, in animal and fishery products by liquid chromatography with mass spectrometry (LC-MS). The sample was homogenized with 1 mol/L dipotassium hydrogenphosphate aqueous solution and extracted with acetone-n-hexane under mildly alkaline conditions. After n-hexane-acetonitrile partitioning using an EXtrelut(?) column, the extract was cleaned up on a tandem SAX/PSA mini-column, and examined by means of fragmenter-voltage-switching ESI-SIM mode LC-MS. Mean recoveries (n=5) of spinosyn A and spinosyn D from eleven kinds of fortified samples at the analyte concentration of 0.01 μg/g and 0.05 μg/g ranged from 76.1% to 93.8% (RSD≤8.7%) and from 75.1% to 104.1% (RSD≤8.6%), respectively.     

A histological study on tissue responses to titanium implantation in rat maxilla: the process of epithelial regeneration and bone reaction

The present study aimed to establish a titanium implantation model using rat maxillae as well as demonstrate the chronological tissue responses to implantation. Pure titanium implants were inserted in the upper first molar extraction sites of Wistar rats 1 month after tooth extraction. The animals were sacrificed at 1 to 30 days postimplantation, and prepared tissue specimens were processed for light microscopy. The removal of implants from tissue blocks was done using 2 methods: mechanical removal or a cryofracture technique. In the early stages, peri-implant tissues showed severe damage to the oral epithelium and collagen bundles with significant inflammatory cell infiltration. The peri-implant epithelium grew apically along the implant by 10 days postimplantation, and regenerated to show a similar feature of junctional epithelium seen in normal rats at 15 days postimplantation, at which time no signs of inflammation were observed. The regenerated collagen bundles in the connective tissue were arranged circumferentially to the implants in the horizontal sections. New bone formation first appeared around the implants at 5 days postimplantation, covering the entire perimeter of implants by 30 days postimplantation. Scanning electron microscopic observations of the surface texture of the removed implants suggest the probability of an adhesive mechanism between the implants and the peri-implant epithelium and/or the alveolar bone. These findings indicate that this experimental model is useful for detailed analysis of peri-implant tissue because of its easy implantation procedure.     

Elimination Transformations for Associative–Commutative Rewriting Systems

To simplify the task of proving termination and AC-termination of term rewriting systems, elimination transformations have been vigorously studied since the 1990s. Dummy elimination, distribution elimination, general dummy elimination, and improved general dummy elimination are examples of elimination transformations. In this paper we clarify the essence of elimination transformations based on the notion of dependency pairs. We first present a theorem that gives a general and essential property for elimination transformations, making them sound with AC-termination. Based on the theorem, we design an elimination transformation called the argument filtering transformation. Next, we clarify the relation among various elimination transformations by comparing them with a corresponding restricted argument filtering transformation. Finally, we compare the AC-dependency pair method with the argument filtering transformation. Parts of this work were done while K. Kusakari was completing his Ph.D. thesis, “Termination, AC-Termination and Dependence Pairs of Term Rewriting Systems,” at Japan Advanced Institute of Science and Technology, School of Information Science (March, 2000). A preliminary version of parts of this article appeared in K. Kusakari, M. Nakamura, Y. Toyama, Argument filtering transformation, Proc. of Int. Conf. on Principles and Practice of Declarative Programming, LNCS 1702 (Springer-Verlag, 1999) pp.47–61.     

Water-filled single-wall carbon nanotubes as molecular nanovalves

It is known that at low temperature, water inside single-wall carbon nanotubes (water-SWNTs) undergoes a structural transition to form tube-like solid structures. The resulting ice NTs are hollow cylinders with diameters comparable to those of typical gas molecules. Hence, the gas-adsorption properties of ice- and water-SWNTs are of interest. Here, we carry out the first systematic investigation into the stability of water-SWNTs in various gas atmospheres below 0.1 MPa by means of electrical resistance, X-ray diffraction, NMR measurements and molecular dynamics calculations. It is found that the resistivity of water-SWNTs exhibits a significant increase in gas atmospheres below a critical temperature Tc, at which a particular type of atmospheric gas molecule enters the SWNTs in an on-off fashion. On the basis of this phenomenon, it is proposed that water-SWNTs can be used to fabricate a new type of molecular nanovalve.