Architecture of Mixed Calcium Oxalate Dihydrate and Monohydrate Stones

Calcium oxalate dihydrate (COD) and monohydrate (COM) are the most frequent constituents of urinary stones, and there still exist some questions about the interrelation between the two hydrates. Architecture of mixed COD and COM stones was observed by electron microscopy to solve the questions. The fractured surface of a stone is composed of the fractured face of the crystals. In this situation a morphological criterion of typical dipyramid shape is useless to identify COD. But we could identify COD using the partial dissolution method, which etched square pits on COD crystals. COD and COM formed distinctly separate layers. COD was always found in the stone surface and COM in the center. The stone surface was covered by a thick layer of organic matrix, and the intercrystalline space was filled with matrix. The crystals were grown thrusting the matrix aside to minimize the space. Although COD is more soluble than COM, the urine contains specific substances that favor the formation of COD. Supposing the stone matrix excludes these substances selectively, the gel-state matrix provides a preferable condition for COM formation. This hypothesis is suitable to explain the high incidence of COM stones. An abrupt change of the crystalline constituent can be explained by COD crystal deposition on COM stones. Frequent COD crystalluria can explain why COD is always found in the stone surface. Once the stone surface is covered with COD crystals, they continue to grow in the gel-state matrix or deposit further to form the bulk of the stone

Design report of the KISS-II facility for exploring the origin of uranium

One of the critical longstanding issues in nuclear physics is the origin of the heavy elements such as platinum and uranium. The r-process hypothesis is generally supported as the process through which heavy elements are formed via explosive rapid neutron capture. Many of the nuclei involved in heavy-element synthesis are unidentified, short-lived, neutron-rich nuclei, and experimental data on their masses, half-lives, excited states, decay modes, and reaction rates with neutron etc., are incredibly scarce. The ultimate goal is to understand the origin of uranium. The nuclei along the pathway to uranium in the r-process are in "Terra Incognita". In principle, as many of these nuclides have more neutrons than 238U, this region is inaccessible via the in-flight fragmentation reactions and in-flight fission reactions used at the present major facilities worldwide. Therefore, the multi-nucleon transfer (MNT) reaction, which has been studied at the KEK Isotope Separation System (KISS), is attracting attention. However, in contrast to in-flight fission and fragmentation, the nuclei produced by the MNT reaction have characteristic kinematics with broad angular distribution and relatively low energies which makes them non-amenable to in-flight separation techniques. KISS-II would be the first facility to effectively connect production, separation, and analysis of nuclides along the r-process path leading to uranium. This will be accomplished by the use of a large solenoid to collect MNT products while rejecting the intense primary beam, a large helium gas catcher to thermalize the MNT products, and an MRTOF mass spectrograph to perform mass analysis and isobaric purification of subsequent spectroscopic studies. The facility will finally allow us to explore the neutron-rich nuclides in this Terra Incognita.Comment: Editors: Yutaka Watanabe and Yoshikazu Hirayam