Effect of impurities in charge-exchange carbon foil on foil thickness reduction

Carbon thin foils are commonly used as a charge stripping material in particle accelerators. Depending on the original foil thickness, changes in thickness during beam irradiation vary: thin foils (∼10 μg/cm²) thicken by build-up, medium thickness foils (∼15 μg/cm²) remain unchanged, and thick foils (∼20 μg/cm²) become thinner. The thickness reduction differs even under identical manufacturing processes and conditions.The factor causing foil thinning is unknown. On the basis of the low sputtering rate of carbon, it can be said that impurities contained in the foil cause foil thinning.Carbon foils contain impurities such as water. These impurities dissociate and combine with carbon and then evaporate. Taking this into consideration, we examined the gas composition during beam irradiation, to determine which impurity causes foil thinning. As a result, we found that oxygen contained in the foil plays a role in foil thinning.     

Electrical resistance change and crack behavior in carbon nanotube/polymer composites under tensile loading

This paper studies the electrical and mechanical responses of cracked carbon nanotube (CNT)-based polymer composites. Tensile tests were performed on single-edge cracked plate specimens of the nanocomposites at room temperature and liquid nitrogen temperature (77 K), and the electrical resistance change of the specimens was monitored. An analytical model based on the electrical conduction mechanism of CNT-based composites was also developed to predict the resistance change resulted from crack propagation. The crack induced resistance change was calculated, and a comparison of the analytical predictions against the experimental data was made to validate the applicability of the model. In addition, the fracture properties of the nanocomposites were assessed in terms of the J-integrals using an elastic-plastic finite element analysis.     

Synthesis of high concentration colloid solution of silica-coated AgI nanoparticles

Methods for high concentration silica-coated silver iodide (AgI/SiO2) particles, which could be practically used as X-ray contrast agent, were examined. The first was a single-step method, which was to prepare AgI nanoparticles at an AgI concentration of 5 x 10(-3) M and coat the AgI nanoparticles with silica shell by a St?ber method. The second was a multiple-step method, which was to repeat a step for preparing a AgI/SiO2 particle colloid solution with 10(-3) M AgI 5 times for adjusting a final AgI concentration to 5 x 10(-3) M. In the two methods, dominant particle aggregation took place, though core-shell particles were also produced. The third was a salting-out method, which was to salt out AgI/SiO2 particles in their colloid solution prepared at an AgI concentration of 10(-3) M, remove supernatant by decantation, and redisperse the particles in a fresh solvent. Consequently, AgI/SiO2 particles with an AgI concentration as high as 0.05 M were successfully prepared with the salting-out method, and their core-shell structure was not damaged during the salting-out.     

Development of a Digital Signal Processing System for the X-Ray Microcalorimeter Onboard ASTRO-H (II)

The Pulse Shape Processor is a digital signal processing electronics for the microcalorimeter instrument onboard ASTRO-H. Receiving digitized waveform (14?bit, 12.5?kHz sample) from 2×18 channels, two identical units of PSP-A and -B trigger X-ray events, assign five kinds of event grade, and perform optimal filtering to measure energy deposit on the 6×6 microcalorimeter pixels. One unit of PSP is composed of one FPGA board and two CPU boards. This paper describes the event processing algorithm to fulfill requirements for the signal processing, and task sharing between FPGA and CPU.     

Indirect air cooling techniques for control rod drives in the high temperature engineering test reactor

The high temperature engineering test reactor (HTTR) is the first high-temperature gas-cooled reactor in Japan with reactor outlet gas temperature of 950 °C and thermal power of 30 MW. Sixteen pairs of control rods are employed for controlling the reactivity change of the HTTR. Each standpipe for a pair of the control rods, which is placed on the top head dome of the reactor pressure vessel, contains one control rod drive mechanism. The control rod drive mechanism may malfunction because of reduction of the electrical insulation of the electromagnetic clutch when the temperature exceeds 180 °C. Because 31 standpipes stand close together in the standpipe room, 16 standpipes for the control rods, which are located at the center, should be cooled effectively. Therefore, the control rod drives are cooled indirectly by forced air circulation through a pair of ring-ducts with proper air outlet nozzles and inlets. Based on analytical results, a pair of the ring-ducts was installed as one of structures in the standpipe room. Evaluation results through the rise-to-power test of the HTTR showed that temperatures of the electromagnetic clutch and the ambient helium gas inside the control rod standpipe should be below the limits of 180 and 75 °C, respectively, at full power operation and at the scram from the operation.     

Serial magnetic resonance imaging shows separate medial and lateral medullary infarctions resulting in the hemimedullary syndrome

PURPOSE: To report two cases in which cystoid macular edema developed after initiation of topical latanoprost for glaucoma. METHODS: Case reports. One pseudophakic eye in each of two patients treated with latanoprost for glaucoma developed decreased vision and cystoid macular edema. Latanoprost was discontinued, and the cystoid macular edema was treated with topical corticosteroids and ketorolac. RESULTS: After discontinuing latanoprost and starting corticosteroids and ketorolac, visual acuity improved from counting fingers to 20/60 in one patient's left eye and from 20/100 to 20/25 in the other patient's right eye. The macular edema resolved in both eyes. CONCLUSIONS: Topical latanoprost may be associated with cystoid macular edema; this may be related to a prostaglandin-like action.     

Rheological Characteristics of Halberd Wheat Starch

The non‐Newtonian behavior and dynamic viscoelasticity of Halberd wheat starch (23.0% amylose content) pastes were determined with a rheogoniometer. The flow curves, at 25°C, of Halberd starch pastes showed plastic behavior at concentrations of more than 4.0%. The shear viscosity of the starch pastes decreased gradually with an increase in temperature at concentrations less than 4.0%, but remained constant at a concentration of 5.0%. The storage modulus of the starch pastes increased with increasing concentration and remained high during increase in temperature up to 80°C. Almost the same storage modulus was observed upon addition of urea (4.0 M) to the paste at low temperature (0°C), and the modulus stayed at a large value with increase in temperature up to 60°C, which was estimated to be a transition temperature; then it decreased rapidly with further temperature increase. A transition temperature of 60°C was also observed in the dynamic viscosity. A very large storage modulus and dynamic viscosity were observed in alkaline solution (0.05 M NaOH) at low temperature (0°C), both quantities decreased slightly with increase in temperature up to 25°C, which was estimated to be a transition temperature, then decreased rapidly with further increase in temperature. A possible intermolecular hydrogen bonding between amylose and amylopectin molecules is proposed.     

Distinct interleukin-1beta-converting enzyme family proteases mediate cisplatin- and staurosporine-induced apoptosis of mouse proximal tubule cells

Interleukin-1beta converting enzyme (ICE) family proteases (caspases) are known to be implicated as important effectors of apoptotic pathways. The purpose of this study was to elucidate the role of ICE family proteases in apoptosis of mouse cells derived from the terminal proximal tubule (S3) treated with cisplatin, an anti-tumor drug, or staurosporine, a protein kinase C inhibitor. For this purpose, we measured the activities of ICE family proteases and examined the effects of tetrapeptide and viral ICE family protease inhibitors on the activities of ICE family proteases in and the degree of apoptosis of S3 cells treated with cisplatin and staurosporine. RT-PCR analysis revealed that S3 cells as well as mouse kidney express mRNA for ICE and CPP32, an ICE family protease. Results of enzymatic analysis, determination the degree of DNA fragmentation and cytotoxicity test suggest that CPP32 mediates cisplatin-induced apoptosis of S3 cells, whereas ICE family proteases other than CPP32 mediate staurosporine-induced apoptosis of S3 cells. In conclusion, distinct ICE family proteases mediate apoptosis of mouse proximal tubule cells depending on the stimuli to which the cells are exposed.     

Interspecific Pheromone Cross-Attraction Among Soybean Bugs (Heteroptera): Does Piezodorus hybneri (Pentatomidae) Utilize the Pheromone of Riptortus clavatus (Alydidae) as a Kairomone?

The chemical and ecological function of cross-attraction of Piezodorus hybneri (Pentatomidae) to the Riptortus clavatus (Alydidae) pheromone (a mixture of three components) was studied. In a field attraction test using traps with synthetic pheromone components, P. hybneri was attracted to (E)-2-hexenyl (E)-2-hexenoate, a component of the R. clavatus pheromone. Other components had neither an additive nor a synergistic effect on the attraction of P. hybneri. Neither (E)-2-hexenyl (E)-2-hexenoate nor other components of the R. clavatus pheromone were detected in volatiles or whole-body extracts of P. hybneri adults by gas chromatographic analysis. In addition, (E)-2-hexenyl (E)-2-hexenoate could not be found in volatiles of soybean plants. Therefore, it appears that P. hybneri responds to a component of the R. clavatus pheromone that is not emitted by P. hybneri itself. We discuss this interspecific pheromone cross-attraction of the soybean bug and hypothesize that P. hybneri utilizes the pheromone of its competitor as a kairomone for host location.     

Chemical Fingerprinting of Heat Stress Responses in the Leaves of Common Wheat by Fourier Transform Infrared Spectroscopy

Wheat (Triticum aestivum L.) is known to be negatively affected by heat stress, and its production is threatened by global warming, particularly in arid regions. Thus, efforts to better understand the molecular responses of wheat to heat stress are required. In the present study, Fourier transform infrared (FTIR) spectroscopy, coupled with chemometrics, was applied to develop a protocol that monitors chemical changes in common wheat under heat stress. Wheat plants at the three-leaf stage were subjected to heat stress at a 42 °C daily maximum temperature for 3 days, and this led to delayed growth in comparison to that of the control. Measurement of FTIR spectra and their principal component analysis showed partially overlapping features between heat-stressed and control leaves. In contrast, supervised machine learning through linear discriminant analysis (LDA) of the spectra demonstrated clear discrimination of heat-stressed leaves from the controls. Analysis of LDA loading suggested that several wavenumbers in the fingerprinting region (400–1800 cm⁻¹) contributed significantly to their discrimination. Novel spectrum-based biomarkers were developed using these discriminative wavenumbers that enabled the successful diagnosis of heat-stressed leaves. Overall, these observations demonstrate the versatility of FTIR-based chemical fingerprints for use in heat-stress profiling in wheat.