Radiation-induced polymerization of ethylene in a pilot plant. II. Development of wet-wall process

Radiation-induced polymerization of ethylene using tert-butyl alcohol aqueous solution as a medium was carried out in a pilot plant with 10 liter reactor at pressures of 100 to 400 kg/cm², ethylene feed rates of 1.2 to 11.8 kg/hr, medium feed rates of 0 to 100 liter/hr, dose rates of 0.6 × 10⁵ to 1.4 × 10⁵ rad/hr, and at room temperature. The space-time yield and molecular weight of polymer were in the range of 1.2 to 16.7 g/liter hr and 6 × 10³ to 2 × 10⁵, respectively. The space-time yield and molecular weight increased with pressure and mean residence time. The space-time yield was the maximum at an ethylene molar fraction of 0.5. The produced polymer was continuously taken out from the high-pressure system as a slurry. The amount of deposited polymer to the reactor wall was markedly decreased, and five full days continuous operation was successfully performed with the space-time yield of 13.5 g/liter hr.     

CO2 Decomposition by Oxide Ceramics Intercalated in Layered Compound

Iron oxide polymers intercalated and/or loaded within täniolite have been studied as a CO₂ decomposition medium. Fe²⁺ was exchanged for Li⁺ in täniolite, oxidized by air-bubbling at 60°–70°C. The basic d -spacing (13.75 Å in the Li⁺ form) was expanded to give 14.86 Å in the Fe²⁺ form. Oxidation by air in the form of suspension gave a 15.3-Å phase, which was ascribed to formation of magnetite within the interlayer. The interlayer distance of the intercalated phase remained the same upon heating at 300°C. The magnetite–intercalated täniolite was heated to activate in a H₂ and/or H₂O steam. CO₂ decomposition reactivity at 300°C has been evidenced by evolution of CO gas. The high reactivity for CO₂ decomposition is ascribed to the highly dispersed iron oxide ceramics within the interlayer of täniolite Li[(Mg₂Li)(Si₄O₁₀)]F₂ n H₂O.     

Workspace mapping based on multisensor information fusion using heterogeneous onboard sensors

In recent years, multiple robot systems that perform team operations have been developed. These robot systems are expected to execute complicated tasks smoothly in a given congested workspace. In this article, we propose a workspace mapping algorithm using ultrasonic stereo sonar and an image sensor in order to operate the mobile robots among obstacles. This workspace mapping algorithm involves two steps: (1) the position detection of obstacles using ultrasonic stereo sonar, and (2) the shape detection of obstacles using an image sensor. While each robot moves around in the given workspace, the two steps of the mapping algorithm are repeated and sensor data are collected. The robot measures the distance and the direction of obstacles using ultrasonic stereo sonar. The shape of obstacles is also captured using an onboard image sensor. A workspace map is created based on the sensor data accumulated from the proposed method, and successful results are also obtained through experiments.     

Disease proteomics of endocrine disorders revealed by two-dimensional gel electrophoresis and mass spectrometry

Endocrine disorders such as dwarfism and diabetes show abnormalities in many different organs even if a certain hormone is the primary cause of the disease. One of the aims of proteomics is to elucidate an abnormal hormone network underlying dysfunction in the disease through quantitative and qualitative proteome analyses of various organs. In a comprehensive study of the rdw rat with hereditary dwarfism, we found the accumulation of ER proteins in the rdw thyroid. Contrary to the initial notion that the dwarfism of the rat was caused by genetic mutations related to pituitary hormones, the primary cause is a missense mutation in the thyroglobulin gene. To understand at the protein level cellular damage caused by oxidative stress, we developed a proteomic method and applied to detecting protein carbonyls in various organs of a diabetes model OLETF rat. The method would provide a means toward clarifying a comprehensive view of oxidative modifications of proteins in diabetes. We review 2-DE-based disease proteomics of endocrine disorders in general, with particular attention paid to our proteome projects by a 2-DE method with an agarose IEF gel in the first dimension (agarose 2-DE) and LC-MS/MS.     

Study on long-term radiation exposure analysis after the Fukushima Dai-ichi nuclear power plant accident: validation of the EU long-term radiation exposure model (ERMIN)

The Fukushima Dai-ichi nuclear power plant accident led to the dispersion of radioactive material by wind that resulted in soil and air pollution over a wide area. Even now, more than 150,000 people in Fukushima prefecture are still relocated from their homes. In order to estimate how long such relocation might continue, we estimated radiation exposures for the 10 years following the accident that occurred on 12 March 2011, using European model for inhabited areas (ERMIN) developed by a partnership of several European organizations. We validated the estimated results of long-term radiation exposure with the observed data at 1, 2 and 3 years after the nuclear accident. We analyzed the deposition velocity and re-suspension coefficient using the observed data on air concentration, amount of falling dust and soil contamination, and compared them with the published data.     

Difference in precipitation rates of air-borne salts collected by the dry gauze method and the Doken tank method

This study compares the precipitation rates of air-borne salts analyzed by the dry gauze method (JIS Z2382) and the Doken (Public Works Research Institute) tank method. Because of the difference of calculation method, direction of prevailing wind causes the difference of salt precipitation rates by these methods. In addition, the Doken tank method has lower capture ability for air-born salt than the dry gauze method under the condition of low supply of air-born salt. While, air-born salt with wet deposition potentially increases salt precipitation of the Doken tank method. As a result, these methods yield different salt precipitation rates.     

Synthesis of single-walled carbon nanotubes using laser-vaporized metal nanoparticle catalyst

SWNTs were synthesized by laser-vaporized CCVD (catalytic chemical vapor deposition). The diameter distributions and the abundance of SWNTs synthesized at different temperatures and using different catalysts were investigated by Raman spectroscopy. Further, this technique was compared with other synthesis techniques (laser-oven and conventional-alcohol CCVD), and C₆₀ was synthesized simultaneously as a byproduct only using the laser-oven technique. With increasing synthesis temperature, the diameter distribution shifted towards larger diameters, and the G/D ratio became larger as the synthesis temperature increased to 1000°C. Ni, Co, and Fe played a catalytic role, though Fe was less effective under our experimental conditions. The diameter distribution of SWNTs synthesized with the Fe catalyst was shifted to smaller values compared to those synthesized with Ni or Co catalysts.     

Efficient affinity maturation of antibodies in an engineered chicken B cell line DT40-SW by increasing point mutation

The chicken B cell line DT40 undergoes hypermutation of immunoglobulin variable region (IgV) genes during culture, thereby constituting an antibody (Ab) library. We previously established an in vitro Ab generation system using an engineered line DT40-SW whose hypermutation machinery can be switched on and off. Abs for various antigens (Ags) can be obtained from the DT40-SW library and the specificity of the Ag-specific clones can be stabilized by stopping hypermutation. Furthermore, the affinity of obtained monoclonal Abs (mAbs) can be improved through further mutation followed by selection, a process analogous to “affinity maturation” that occurs in vivo. Although gene conversion dominantly diversifies the IgV genes in DT40 cells, point mutation is considered to be more favorable for fine-tuning Ab properties during affinity maturation. Here, we examined whether affinity maturation occurs more efficiently when the hypermutation pattern was transformed from gene conversion into point mutation in DT40-SW cells. To this end, we disrupted the XRCC3 gene that is essential for gene conversion. It was found that hemizygous disruption of the XRCC3 gene was sufficient to increase the point mutation frequency. Since hemizygous disruption is conducted more easily, we tested whether the XRCC3 (+/−) mutant generates high-affinity Abs through affinity maturation more efficiently than the wild type. Using this affinity maturation technique, we generated an improved 4-hydroxy-3-nitrophenylacetyl-specific mAb with ∼ 600-fold lower K_D than that of the original mAb. Taken together, hemizygous disruption of the XRCC3 gene is considered to be useful for obtaining high-affinity mAbs from DT40-SW cells though affinity maturation.     

Wettability Improvement by Plasma Irradiation and Its Applications to Phase-Change Phenomena

Plasma irradiation is one of the techniques to improve surface wettability. This technique can be used to enhance heat transfer of liquid–vapor phase change. For instance, evaporation of a water droplet can be enhanced by plasma irradiation. The relation between plasma irradiation time and contact angle was examined first for three metals and then the lifetime of a water drop on a hot surface was measured changing the surface wettability by plasma irradiation. The lifetime of the water drop decreased and the wetting limit temperature increased with the increasing irradiation time of plasma. Hydrophilicity by plasma irradiation is not a permanent effect but it will be useful for enhancement of cooling of hot metal.