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We report detections of thermal X-ray line emission and proper motions in the supernova remnant (SNR) RX J1713.7-3946, the prototype of the small class of synchrotron dominated SNRs. Based on deep XMM-Newton observations, we find clear line features including Ne Lyα, Mg Heα, and Si Heα from the central portion of the remnant. The metal abundance ratios suggest that the thermal emission originates from core-collapse SN ejecta arising from a relatively low-mass (≲20 M⊙) progenitor. In addition, using XMM-Newton observations on a 13 yr time interval, we have measured expansion in the southeastern rim to be ~0.75″ yr−1 or ~3500 km s−1 at a distance of 1 kpc. Given this, we derive an upstream density to be ~0.01 cm−3, compatible with the lack of thermal X-rays from the shocked ambient medium. We also estimate the age of the remnant to be ~1200–1600 yr, roughly consistent with the idea that RX J1713.7-3946 is the remnant of SN 393.
In order to facilitate the measurement of liquid-water content of snow in high mountains, a portable calorimeter named “Endo-type snow-water content meter” was developed. It is composed of a metal-coated container made of insulating materials and a lid of the container with a small-thermistor thermometer. Its strong points are its light weight, small size and easy fabrication with cheap materials. The total weight of the device is as light as 250 g, which is less than 10% of the snow-water content meter widely used in Japan (Akitaya-type snow-water content meter). The results of experiments have revealed that the device is capable of measuring the liquid-water content within 2 minutes with an accuracy of 2% by weight.
Efficient water desalination constitutes a major challenge for the next years and reverse osmosis membranes will play a key role to achieve this target. In this work, a high-performance reverse osmosis nanocomposite membrane was prepared by interfacial polymerization in presence of multiwalled carbon nanotubes. The effect of carbon nanotubes on the chlorine resistance, antifouling and desalination performance of the nanocomposite membranes was studied. We found that the addition of carbon nanotubes not only improved the membrane performance in terms of flow and antifouling, but also inhibited the chlorine degradation of these membranes. Several reports have acknowledged the benefits of adding carbon nanotubes to aromatic PA nanocomposite membranes, but little attention has been paid to the mechanisms related to the improvement of flow rate, selectivity and chlorine tolerance. We carried out a comprehensive study of the chemical and physical effects of carbon nanotubes on the fully crosslinked polyamide network. The chemical structure, chlorine resistance and membrane degradation was studied by several analytical techniques, permeation and fouling studies, whereas the microstructure of the nanocomposite was studied by small and wide angle X-ray scattering, high resolution transmission electron microscopy, and molecular dynamics. We found that the addition of the nanotube affects the interfacial polymerization, resulting in a polymer network with smaller pore size and higher sodium and chlorine rejection. We simulated the hydration of the membrane in seawater and found that the radial distribution function of water confined in the pores of the nanocomposite membrane exhibited smaller clusters of water molecules, thus suggesting a dense membrane structure. We analysed the network mobility and found that the nanotube provides mechanical stability to the polymer matrix. This study presents solid evidence towards more efficient and robust reverse osmosis membranes using carbon nanotubes as mechanical reinforcing and chlorine protection additive.
Four patients presented with hemiballism-hemichorea as a clinical manifestation of white matter ischemia. These patients illustrate “positive” motor phenomena rather than limb weakness as a consequence of cerebral ischemia. In each patient, the involuntary movements disappeared following worsening of paresis. Subcortical white matter infarction in three patients and hemodynamic hypo-perfusion in the cerebral hemisphere contralateral to dyskinetic movements were possible causes. Neuroradiologically, none had pathological changes in the vicinity of the subthalamic nucleus. We presume from these observations that ischemia of the subcortical white matter, without involvement of the basal ganglia or the subthalamic nucleus, may cause hemiballism-hemichorea
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