[en] Complexes made of DNA and Cyclo-Pt bound to plasmid DNA, were placed in aqueous solution and irradiated with monochromatic X-rays in the range E=8.5-13 keV, including the resonant photoabsorption energy of the L_III shell of the platinum atom. The number of single- and double-strand breaks (ssb and dsb) induced by irradiation on a supercoiled DNA plasmid was measured by the production of circular-nicked and linear forms. In order to disentangle the contribution of the direct effects imparted to ionization, and the indirect effects due to a free radical attack, experiments have been performed in the presence of a small concentration (64 mmol l^-1) of hydroxyl free radical scavenger dimethyl sulfoxide (DMSO). An enhancement of the number of ssb and dsb is observed when the plasmids contain the Pt intercalating molecules. Even when off-resonant X-rays are used, the strand break efficiency remains higher than expected based upon the absorption cross-section, as if the Pt bound to DNA is increasing the yield of strand breaks. A mechanism is suggested, involving photoelectrons generated from the ionization of water which efficiently ionize Pt atoms. This observation may provide an insight to understanding the effects of new radiotherapy protocols, associated chemotherapeutic agents such as cisplatin and ordinary radiotherapy for tumoral treatments

[en] Highly pure single crystals of YIG were obtained by an FZ method, and a remarkable photoinduced change in permeability was observed. The permeability of samples held at a temperature of 77 K was decreased by more than 90% by illumination. The photoinduced change remained, to some extent, at temperatures up to about 260 K. By annealing at 1100 degrees C (in an oxygen atmosphere for six hours) in the sample preparation stage, the magnitude of the effect was reduced to 40%. After samples at 77 K were strongly illuminated, the loss factor below 5 kHz showed a pair of peaks, in contrast with the flat curve for unilluminated samples on warming to 300 K. The activation energies corresponding to the peaks were found to be 0.3 and 0.1 eV. The mechanism of the effect is discussed in relation to relaxation processes related to these peaks, and F⁰ centers, or oxygen vacancies with two trapped electrons, are though to play an essential role

[en] The decays of ⁶⁴Cu incorporated in human malignant (A549) or monkey non-malignant (CVI) cells lead to cell death. When plotted as a function of the radioactivity introduced in the growth medium (μCi/ml at t = O), the residual colony-forming capability decreases exponentially. The slope of the corresponding curve is steeper for A549 than for CV1 cells. Different data show that the cellular lethal event is a consequence of ⁶⁴Cu transmutation and not of the irradiation by the simultaneously emitted β^- and β⁺ particles. Liquid holding results show that the lethal event is irreparable. The decays of ⁶⁷Cu, another radioisotope of copper, lead to cell death with the same exponential survival curve and the same lethal efficiency as for ⁶⁴Cu, in spite of their different decay schemes. The lethal efficiency of both copper isotopes is close to that of ¹²⁵I utilized in the form of iododeoxyuridine under the same experimental conditions as ⁶⁴Cu and ⁶⁷Cu. (author)

[en] Reliability of a steam generator is essentially required to improve Pressurized Water Reactor (PWR) Power Plant availability. It is necessary to know the thermal hydraulic phenomena in a steam generator exactly. This paper describes verification of three dimensional analytical computer code by experimental data. Experimental data are obtained by steam-water two phase flow test with 10 MW model steam generator and Freon thermal hydraulic test, etc. Main data are void fraction, temperature and velocity distributions. It is confirmed that there is ability to evaluate thermal hydraulic behaviors in a steam generator with verified analytical computer code

[en] A highly purified YIG single crystal is obtained by a floating zone method and found to show a remarkable photoinduced effect on an initial permeability μ'. Besides, the temperature vanishing the effect is found to be 250 to 260 K, which is higher by about 50 K than previously reported. A pair of Fe²⁺-oxygen vacancy is supposed to be a photomagnetic center in this crystal. Furthermore, photoinduced double peaks on tan δ-temperature curve for this sample are, for the first time, observed in the temperature range 77 to 300 K. This observation is suggestive of two limited migration modes of electrons. Several alternative models are introduced to explain the phenomenon, including a possible mechanisms of the photomagnetic center. For comparison, the behavior of the sample grown by flux method is also reported. (author)

[en] Intracranial artery dissection is an uncommon but possible cause of ischemic stroke, and is usually diagnosed based on imaging findings such as mural hematoma and dissection flap. However, it is challenging to recognize the underlying dissection in cases of acute large vessel occlusion. In this report, we present a case of acute internal carotid artery occlusion, in which the underlying dissection of the paraclinoid segment was found during the thrombectomy procedure. Two thrombectomy procedures failed to recanalize the acute internal carotid artery occlusion without removing any clot. Angiography performed during a Trevo stent retriever deployment in the first pass showed obscure contrast defects in the stent strut with temporary flow restoration. In the next pass, the appearance of the contrast defects changed and a parallel linear contrast appeared on the outside of the vessel wall. These angiographic findings were identified as mural hematoma and dissection flap, indicating dissection of the paraclinoid as the cause of the occlusion. During antiplatelet loading and preparation of a dedicated intracranial stent, the Trevo stent retriever was left deployed again at the occlusion site to maintain the blood flow. After permanent stenting with an Enterprise stent, angiography revealed complete recanalization. The patient recovered fully after the procedure. In the present case, stent retriever deployment revealed the hallmarks of dissection on angiography, such as mural hematoma, dissection flap, and temporal morphological changes, by restoring the blood flow temporarily. Such angiographic findings can provide useful information on the occlusion characteristics and real-time feedback for optimal treatment strategy