Induced radioactive nuclides of 10-MeV radiotherapy accelerators detected by using a portable HP-Ge survey meter

The radioactivation of linear accelerator components for radiation therapy is interest for radiation protection in general, and particularly, when decommissioning these structures. The energy spectra of gamma rays emitted from the heads of two accelerator models, EXL-15SP and Clinac iX, after 10-MeV X-ray irradiation, were measured using a high-purity germanium semiconductor survey meter. After spectrum analyses, activities of (24)Na, (28)Al, (54)Mn, (56)Mn, (57)Ni, (58)Co, (60)Co, (64)Cu, (65)Zn, (122)Sb, (124)Sb, (181)W, (187)W, (196)Au, and (198)Au were detected. One centimetre deep dose-equivalent rate of the heads of the linear accelerator was measured using the survey meter. The dose rate decreased to ～10 % of its initial rate after 1 week. Long-term activations were few, the radioactivity level was low, and a cooling time of several days was effective for reducing dose rate to an acceptable level for decommissioning.     

Preferential Oxidation of CO Impurities in the Presence of H2 on NiO-Loaded and Unloaded TiO2 Photocatalysts at 293 K

The photocatalytic preferential oxidation of CO with O₂ in the presence of H₂ (photo-PROX) was found to proceed efficiently on the NiO-loaded TiO₂ (NiO/TiO₂) catalyst under UV light irradiation at 293 K. NiO/TiO₂ exhibited higher CO conversion as well as CO₂ selectivity for a photo-PROX reaction than the original unloaded TiO₂ (P-25). Various spectroscopic investigations have revealed that the small NiO clusters formed on TiO₂ play an important role in the enhancement of CO oxidation activity in this reaction.     

A study of generator system selection for large wind turbine generator system

This paper focuses on selection of wind turbine generation systems that include generators, converters, and gears. We study three systems: a permanent magnet generator (PMG) system, a doubly‐fed generator (DFG) system, and a synchronous generator (SYG) system in terms of the system efficiencies and running costs. The system efficiencies and running costs are calculated by considering the relationship between wind power and wind conditions. According to these results, the one‐step gear PMG system is the best choice for a large wind turbine system. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(1): 51–57, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20506     

Study on intelligent humidity control materials: Water vapor adsorption properties of mesostructured silica derived from amorphous fumed silica

The intelligent humidity control materials were synthesized using fumed silica and quaternary alkylammonium surfactant (decyl-, dodecyl-, tetradecyl- and hexadecyl-trimethylammonium chlorides) as a liquid-crystal template under hydrothermal conditions. X-ray diffraction and transmission electron micrographs indicate that a homogeneous hexagonal structure of SiO2 was formed for those products. The mesostructured products had high B.E.T. surface areas between 960 and 1300 m2/g, with uniform mesopore diameters of 2–4nm. These physical quantities were controlled by varying the size of the organic template. Water vapor adsorption isotherms for these materials possess a sharp increase in adsorption when the relative water vapor pressure is at 40–60%. Over this range of pressures, the maximum amount of adsorbed water content is between 40 and 90%. These silicates have the potential to be effectively used as humidity control elements in construction materials.     

Polyethyleneimine/chitosan hexamer-mediated gene transfection into intestinal epithelial cell cultured in serum-containing medium

In search of an efficient nonviral vector, polyethyleneimine (PEI)-based vectors were examined. In general, the transfection efficiency of nonviral vectors is suppressed by serum. Here we show that PEI based vectors, particularly, the chitosan hexamer-PEI vector, could perform efficient gene transfection into intestinal epithelial cells (IEC-6) in the presence of serum. The conjugation order of the two polymers with a plasmid (first, chitosan hexamer; second, PEI) was found to be an important factor in enhancing transfection efficiency.     

Access concentration detection in click logs to improve mobile Web-IR

Effective ranking algorithms for mobile Web searches are being actively pursued. Due to the peculiar and troublesome properties of mobile contents such as scant text, few outward links, and few input keywords, conventional Web search techniques using bag-of-words ranking functions or link-based algorithms are not good enough for mobile Web searches. Our solution is to use click logs to clarify access-concentrated search results for each query and to utilize the titles and snippets to expand the queries. Many previous works regard the absolute click numbers as the degree of access concentration, but they are strongly biased such that higher-ranked search results are more easily clicked than lower-ranked ones. Therefore, it is considered that only higher-ranked search results are access-concentrated ones and that only terms extracted from them can be used to expand a query. In this paper, we introduce a new measure that is capable of estimating the degree of access concentration. This measure is used to precisely extract access concentration sites from many search results and to expand queries with terms extracted from them. We conducted an experiment using the click logs and data from an actual mobile Web search site. Results obtained show that our proposed method is a more effective way to boost the search precision than using other query expansion methods such as the top K search results or the most-often-clicked search results.     

Work schedule differences in sleep problems of nursing home caregivers

Nursing home caregivers (n=775; 604 women; mean age 33.6 years) were studied to examine how work schedules affect their sleep. The shift group (n=536) worked under a rotating two-shift system (n=365), a rotating three-shift system (n=66), or other types of shifts (n=78). The non-shift group included 222 caregivers. Participants completed a questionnaire about working conditions, sleep problems, health, lifestyle, and demographic factors. The two-shift caregivers reported the highest levels of difficulty initiating sleep (DIS, 37.6%), insomnia symptoms (43.0%), and poor quality of sleep (24.9%) among the groups. Adjusted odds ratios for these problems were significantly greater for the two-shift caregivers than for non-shift counterparts: DIS (odds ratio 2.86, 95% confidence interval 1.57-5.20), insomnia symptoms (2.33, 1.36-4.02), and poor sleep quality (2.15, 1.09-4.22). Our data suggest that working under a rotating two-shift system, which has a longer night shift, is associated with an elevated risk of sleep problems for nursing home caregivers.     

Narrow‐gap field‐sequential TN‐LCD with and without nanoparticle doping

Abstract— The fabrication and demonstration of field‐sequential‐color (FSC) LCDs using modules of narrow‐gap twisted‐nematic (NTN) LCDs with and without doping of newly synthesized PγCyD‐ZrO² nanoparticles is reported. Two types of FSC‐LCDs are demonstrated: one is a direct multiplexed NTN‐LCD and the other is TFT driven. The advantages of FSC‐LCDs include their high legibility even under direct sunlight, and the mechanism for the doping of nanoparticles in LCDs is discussed.