Parallel two-step phase-shifting digital holography

We propose a parallel two-step phase-shifting digital holography technique capable of instantaneous measurement of three-dimensional objects, with a view toward measurement of dynamically moving objects. The technique is based on phase-shifting interferometry. The proposed technique carries out the two-step phase-shifting method at one time and can be optically implemented by using a phase-shifting array device located in the reference beam. The array device has a periodic two-step phase distribution, and its configuration is simplified compared with that required for three-step and four-step parallel phase-shifting digital holographies. Therefore the optical system of the proposed technique is more suitable for the realization of a parallel phase-shifting digital holography system. We conduct both a numerical simulation and a preliminary experiment in the proposed technique. The results of the simulation and the experiment agree well with those of sequential phase-shifting digital holography, and results are superior to those obtained by conventional digital holography using the Fresnel transform alone. Thus the effectiveness of the proposed technique is verified.     

Environmental contamination and external radiation dose rates from radionuclides released from the Fukushima nuclear power plant

To evaluate the environmental contamination and contributory external exposure after the accident at the Fukushima Nuclear Power Plant (FNPP), the concentrations of artificial radionuclides in soil samples from each area were analysed by gamma spectrometry. Six artificial radionuclides ((131)I, (134)Cs, (137)Cs, (129m)Te, (95)Nb and (136)Cs) were detected in soil samples around FNPP. Calculated external effective doses from artificial radionuclide contamination in soil samples around FNPP were 1.9-2.9 μSv h(-1) (8.7-17.8 mSv y(-1)) in Fukushima city on 22 March 2011. After several months, these calculated external effective doses were 0.25-0.88 μSv h(-1) (2.2-7.6 mSv y(-1)) in Fukushima city on 29 June 2011. The present study revealed that the detected artificial radionuclides around FNPP mainly shifted to long-lived radionuclides such as radioactive caesium ((134)Cs and (137)Cs) even though current levels are decreasing gradually due to the decay of short-lived radionuclides such as (131)I, (129m)Te, (95)Nb and (136)Cs. Thus, radiation exposure potency still exists even though the national efforts are ongoing for reducing the annual exposure dose closer to 1 mSv, the public dose limit. Long-term environmental monitoring around FNPP contributes to radiation safety, with a reduction in unnecessary exposure to the residents.     

Influence of Cu on nanostructure of Fe3O 4 particles

Cu is effective on the refinement of Fe₃O₄ rust particles but its mechanism is not clarified. In this study, the influence of Cu on the nanostructure of Fe₃O₄ particles was investigated through a detailed analysis of the characteristics of the artificially synthesized Fe₃O₄ particles formed with Cu²⁺ by various means. X‐ray absorption fine structure analysis showed that Cu is substituted for octahedral Fe and exists as Cu_xFe_(3‐x)O₄ in Fe₃O₄. The first‐principle calculation showed that lattice strain resulted around the substituted Cu. These results suggest that this lattice strain around substituted Cu inhibited the lattice growth and contributed to the refinement of Fe₃O₄ particles.     

稻田花岗岩中的流体包裹体及由其导致高温条件下微小裂纹的形成

几乎在所有花岗岩的石英及长石中都含有很多流体包裹体。通过常温及高温显微镜观察，查明了稻田花岗岩中流体包裹体的初始分布状态，并发现在高温条件下，由于流体包裹体的爆裂而导致花岗岩中微小裂纹的形成。在标准大气压条件下测定了流体包裹体的爆裂温度，研讨了其形状、尺寸、均质化温度等因素对爆裂温度的影响，并根据形态观察掌握了裂纹形成的基本规律。这些特征对于各类花岗岩具有一定的普遍性，能为掌握花岗岩在高温条件下的物理及力学性质提供重要的基础数据，对于高放射性核废料地下深部处理等工程问题具有较大的参考价值。     

Molecular typing to trace Listeria monocytogenes isolated from cold-smoked fish to a contamination source in a processing plant

In this study, Listeria monocytogenes contamination in a cold-smoked fish processing plant in Osaka, Japan, was examined from 2002 to 2004. A total of 430 samples were collected and divided into five categories: raw fish, materials during processing, processing equipment, environment, and finished products. A total of 59 finished products were examined throughout this study. L. monocytogenes was isolated from four of these samples during summer and autumn but was not found during winter or spring. During the warmer seasons, L. monocytogenes was more prevalent on processing equipment, especially slicing machines (8 of 54 samples in summer and autumn versus 1 of 50 samples in winter and spring). L. monocytogenes was not detected on whole skins removed from 23 frozen raw fish. L. monocytogenes strains isolated from 56 samples were characterized by serotyping, pulsed-field gel electrophoresis, and three PCR-based methods. Seventy-seven L. monocytogenes strains were recognized as contaminants of the samples: 2 distinguishable strains were identified in each of 13 samples, 3 strains were identified in 2 samples, 5 strains were identified in 1 sample, and the other 40 strains were identified in 40 samples. Combining the results from these techniques, 77 strains were classified into 13 different types. Three of these types prevailed throughout the plant, and two of the three were also isolated from final products. The DNA subtype found in the product was also found on the slicing machines. Our findings suggest that the slicing machines at this plant were the source of the product contamination. Implementing an appropriate cleaning regime for the slicing machines was effective in preventing contamination.