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Introduction: We analyzed more than 800 small Ryugu grains as a part of the initial analysis team [1]. Their average sizes of grains collected from the first and the second touchdown sites are ~70 and ~50 μm, respectively. In addition, we also investigated one and three large grains from the "chemistry" and the "stone" teams, respectively. Our "sand" team investigated these grains using FE-SEM, (S)TEM, STXM-XANES, nanobeam XANES, nano-CT, and APT. Several updated results investigated by our team and some results as collaborative work between teams will be presented at this meeting [e.g. 2-8]. The main scientific goals of our team are to clarify the mineralogy of the finegrained samples and to reveal the nature of the space weathering of the asteroid Ryugu, which belongs to the most abundant C-type asteroids. The surfaces of Solar System bodies that lack atmospheres are exposed to the space environment and experience gradual alteration, called space weathering [e.g. 9]. Its effects on C-type asteroids are poorly understood [9]. Samples returned from the C-type asteroid Ryugu by Hayabusa2 enable resolution of this issue. Results and discussion: The mineralogy of most Ryugu grains investigated by (S)TEM is similar to that of CI chondrites, which are chemically the most primitive materials in the Solar System. This result is consistent with other recent studies [10-12]. The major modes of space weathering on Ryugu grains are amorphization and partial melting of phyllosilicate surfaces. Reduction from Fe3+ to Fe2+ in phyllosilicates and dehydration decomposition of the phyllosilicates are associated with the space weathering. Although the physical processes that cause space weathering on Ryugu (solar wind irradiation and (micro)meteoroid impact) are identical to those on the Moon and the S-type asteroid Itokawa [13], the results are substantially different from space weathering of these anhydrous airless bodies. Space weathering of Ryugu promotes dehydration of abundant phyllosilicates via decomposition of serpentine and saponite that has already lost interlayer water molecules (H2O) and may, therefore, weaken the 2.7-μm band assigned to hydroxyl (-OH) in reflectance spectra [14]. Therefore, the weak 2.7-μm band of at least a part of C-type asteroids might be caused by space weathering. [ABSTRACT FROM AUTHOR]

Introduction: Solar wind irradiation and micrometeorite bombardments alter the physical, chemical, and optical properties of materials on airless bodies. These modifications are so called space weathering [1]. C-type carbonaceous Ryugue shows variations in reflectance spectra which are likely related to the geologic activity and surface exposure age [2]. Space weathering features in the returned samples will provide key information to interpret the surface evolution of Ryugu. One of the major causes to alter the reflectance spectra of airless bodies is considered to be nanometersized particles of opaque mineral phases (nanophase opaque minerals) produced by space weathering [1]. In this study, we examined the appearance of nanophase opaque minerals in Ryugu grains. Methods: We analyzed two fine Ryugu grains, A104-021002 and A104-028098. These grains were fixed on gold plates with epoxy resin. After the grains were observed by scanning electron microscopy (SEM), electron-transparent sections were extracted from the grain surface using the focused ion beam system. The extracted sections were analyzed by scanning transmission electron microscopy (TEM/STEM). 4D-STEM imaging (electron diffraction mapping using nano-beam) was applied to identify nanometer-sized inclusions. Results: The two Ryugu grains consist mainly of phyllosilicate-rich matrix, iron sulfides, magnetite, and carbonates. SEM observation shows that the phyllosilicate of the two grains have smooth surfaces with tiny bubbles, corresponding to the modified morphologies related to space weathering [3]. The magnetite and iron sulfides have porous surfaces indicative of space weathering [4]. TEM/STEM analysis shows that the phyllosilicate surfaces are coated by modified layers up to ~60 nm in depth (Fig. 1a). 4D-STEM imaging reveals that the surface modified layers are amorphous. Nanophase inclusions are rarely observed in the amorphous layers. STEM-EDS mapping of the phyllosilicate surfaces shows that outer 7-13 nm-wide zone is different in chemical composition from the phyllosilicate substrate (Fig. 1). The outermost rim of A104-021002 includes nanophase particles with high Z-contrast in HAADFSTEM image (Fig. 1b), and is rich in sulfur, iron, and nickel (Fig. 1c). 4D-STEM imaging of the outermost rim shows reflections corresponding to pentlandite and troilite with random orientations. The outermost rim of A104-028098 is rich in iron and has high Z-contrast. 4D-STEM data obtained from the rim shows reflections of troilite. Discussion: The amorphous layers on phyllosilicate are probably produced by solar wind irradiation [3]. Studies of lunar soils and grains from S-type asteroid Itokawa has indicated that the outermost rims with distinct chemical composition correspond to materials deposited from vapors produced by micrometeorite bombardments and solar wind sputtering [1]. Thin deposits including nanophase iron sulfides, pentlandite, and magnetite were produced by the pulsed-laser experiment for carbonaceous chondrite simulating micrometeorite bombardments [5]. Therefore, the outermost rims on Ryugu grains are probably vapor-deposited materials. The nanometer-sized iron sulfides in the vapor deposits can be produced when the sulfur fugacity in the vapor cloud was high enough to condense sulfide minerals [5]. Plausible sulfur source for the high sulfur fugacity may be iron sulfide minerals, because iron sulfides are the second major minerals in Ryugu samples and the space-weathered iron sulfides show the evidence of sulfur loss [4]. The experimentally produced vapor-deposits showed a strongly reddened reflectance slope across the visible to near-infrared wavelengths, because of the opaque nano-particles [5]. The nanophase iron sulfides on Ryugu grains may contribute to the color variations of Ryugu, where surface materials are expected to be reddened with time [2]. The apparent scarcity of nanophase inclusions in the irradiation-damaged rim suggests that vapor deposition processes play an important role for the production of nanophase opaque minerals on Ryugu rather than solar wind irradiation. [ABSTRACT FROM AUTHOR]

The Hayabusa2 spacecraft delivered samples of the carbonaceous asteroid Ryugu to Earth. Some of the sample particles show evidence of micrometeoroid impacts, which occurred on the asteroid surface. Among those, particles A0067 and A0094 have flat surfaces on which a large number of microcraters and impact melt splashes are observed. Two impact melt splashes and one microcrater were analyzed to unveil the nature of the objects that impacted the asteroid surface. The melt splashes consist mainly of Mg-Fe-rich glassy silicates and Fe-Ni sulfides. The microcrater trapped an impact melt consisting mainly of Mg-Fe-rich glassy silicate, Fe-Ni sulfides, and minor silica-rich glass. These impact melts show a single compositional trend indicating mixing of Ryugu surface materials and impactors having chondritic chemical compositions. The relict impactor in one of the melt splashes shows mineralogical similarity with anhydrous chondritic interplanetary dust particles having a probable cometary origin. The chondritic micrometeoroids probably impacted the Ryugu surface during its residence in a near-Earth orbit.

Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe 3+ to Fe 2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (-OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2022.)

The extraterrestrial materials returned from asteroid (162173) Ryugu consist predominantly of low-temperature aqueously formed secondary minerals and are chemically and mineralogically similar to CI (Ivuna-type) carbonaceous chondrites. Here, we show that high-temperature anhydrous primary minerals in Ryugu and CI chondrites exhibit a bimodal distribution of oxygen isotopic compositions: 16 O-rich (associated with refractory inclusions) and 16 O-poor (associated with chondrules). Both the 16 O-rich and 16 O-poor minerals probably formed in the inner solar protoplanetary disk and were subsequently transported outward. The abundance ratios of the 16 O-rich to 16 O-poor minerals in Ryugu and CI chondrites are higher than in other carbonaceous chondrite groups but are similar to that of comet 81P/Wild2, suggesting that Ryugu and CI chondrites accreted in the outer Solar System closer to the accretion region of comets.

We proposed a novel laser-driven short-term heating angioplasty to realize restenosis-suppressive angioplasty for peripheral artery disease. In this study, we investigated the chronic intimal hyperplasia formation after the short-term heating dilatation in vivo, as well as the thermal damage calculation on arterial smooth muscle cells (SMCs). The prototype short-term heating balloon catheter with 5.0, 5.5, 6.0 mm φ in balloon diameter and 25 mm in balloon length were employed. The short-term heating dilatation was performed in porcine iliac arteries with dilatation conditions of 75°C (N=4) and 65°C (N=5) as peak balloon temperature, 18 ± 4s as heating duration, 3.5 atm as balloon dilatation pressure. Four weeks after the balloon dilatation, the balloon-dilated artery segments were extracted and were stained with HE and picrosirius red for histological observation. In the case of 75°C as the peak balloon temperature, neointimal hyperplasia formation was significantly reduced. In this case, the SMCs density in the artery media measured from the HE-stained specimen was 20% lower than that in the reference artery. According to the thermal damage calculation, it was estimated that the SMCs lethality in artery media after the short-term heating angioplasty was 20% in the case of 75°C as the peak balloon temperature. We demonstrated that the short-term heating dilatation reduced the number of SMCs in artery media. We think this SMCs reduction might contribute to the suppression of chronic neointimal hyperplasia.

DNA microspheres formed by self-assembly of DNA three-way junctions with self-complementary sticky-ends undergo an unexpected dynamic transformation from filled spheres into hollow capsules upon addition of cationic surfactants such as cetyltrimethylammonium bromide.

Three strands of 30-mer oligodeoxyribonucleotides (ODNs) were designed to form three-way junctions that possess self-complementary sticky ends. The morphology of self-assembled ODNs in water was observed in situ by confocal laser scanning fluorescence microscopy. The three-way junctions self-assembled into spherical assemblies, in accordance with transmission and scanning electron microscopy. The size of nucleospheres was in the range of several tens of nanometers to micrometers, which varied depending on the concentration of ODNs and added salts. Fluorescence images of spherical ODN assemblies suggested that the nucleospheres possess multiwalled structures. The fluorescence of sodium 1-anilinonaphthalene-8-sulfonate in the presence of nucleospheres revealed that the interior of nucleospheres possesses polarity corresponding to that between methanol and ethanol. A dye-inclusion experiment showed that cationic and even anionic dyes were adsorbed to the interior of the nucleospheres. The dye-included nucleospheres released dyes by thermal dissociation or digestion of the constituent ODNs.

DNA three-way junctions formed from three 30-mer oligonucleotides that contain single-chained self-complementary sticky ends spontaneously self-assemble into 'nucleo-nanocages': the exo- and endo-nuclease digestion experiments indicate that defects such as the single and double strand end structures are absent on the spherical nano-assemblies, providing clear evidence for the closed nanocage structure.

Two phase I studies (CIC-therapy) were conducted in advanced non-small cell lung cancer (NSCLC) to determine the maximum tolerable dose (MTD) of CPT-11 combined with cisplatin and ifosfamide, and MTD of cisplatin combined with CPT-11 and ifosfamide with G-CSF support, respectively. Both regimens were repeated every 4 weeks. G-CSF was administered on days 5 to 18. Eighty-eight patients were registered in both studies. The overall response rate was 59.1%, and the median survival time was 393 days. In all patients enrolled, we examined retrospectively the period of time they could remain at home during chemotherapy. We examined this period divided into day 1-18 and day 18-28 until the third course. Although myelotoxicity occurring during the third course was the most severe, the mean time was 7.1 days (day 1-18 2.2, day 18-28 4.9) for the first course, 10.1 days (day 1-18 4.0, day 18-28 6.0) for the second course, and 11.0 days (day 1-18 4.7, day 18-28 6.3) for the third course. Only two patients came to the hospital because of acute upper respiratory tract infection. Although CIC-therapy was an aggressive chemotherapy with G-CSF support, most of the patients were able to stay at home during chemotherapy.