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Aerostatic bearings are widely used for spindles in ultra-precision machining tools. These spindles consist of a pair of aerostatic thrust bearings and several aerostatic journal bearings. The rotational accuracy of aerostatic spindles depends largely on the arrangement and performance of the individual bearings, but the evaluation of the rotational accuracy is mainly carried out experimentally using a prototype machine, which poses challenges in terms of the time and cost of building a prototype. Therefore, a real need exists to evaluate the spindle characteristics by numerical calculation. In this study, we developed a method to numerically calculate the trajectory of the spindle rotator which is supported by aerostatic bearings. The method was developed to numerically investigate and determine the effects on the rotational accuracy of the spindle during end milling when the cutting force is applied to the rotating rotor. A comparison was made regarding the amount of runout of the rotating shaft when side milling was performed using a spindle with a shaft diameter of 22 mm and a small end mill with a diameter of 1 mm, concerning three different spindles with different arrangements of thrust and journal bearings. The effects of rotational speed, radial depth of cut, and the number of tool teeth on the runout of the rotating shaft were numerically verified. As a result, it was found that a spindle structure in which the thrust bearing is placed on the tool side and the journal bearing span is lengthened is desirable.

International audience; INTRODUCTION: Organic compounds in asteroids and comets contain information about the early history of the Solar System. They could also have delivered organic material to early Earth. The Hayabusa2 spacecraft visited the carbonaceous asteroid Ryugu and collected samples of its surface materials, which were brought to Earth in December 2020. RATIONALE: We investigated the macromolecular organic matter in the Ryugu samples, measuring its elemental, isotopic, and functional group compositions along with its small-scale structures and morphologies. Analytical methods used included spectro-microscopies, electron microscopy, and isotopic microscopy. We examined intact Ryugu grains and insoluble carbonaceous residues isolated by acid treatment of the Ryugu samples. RESULTS: Organic matter is abundant in the Ryugu grains, distributed as submicrometersized organic grains and as organic matter dispersed in matrix. The Ryugu organic matter consists of aromatic carbons, aliphatic carbons, ketones, and carboxyls. The functional group

We propose a variable-magnification full-field x-ray microscope using two Fresnel zone plates (FZPs). By moving the positions of the two FZPs, the magnification can be continuously changed even if the sample and camera positions are fixed. It was demonstrated that the magnification can be changed in the range of 25–150× using a hard x-ray beam at 14.4 keV. Using the first FZP as a convex lens and the second FZP as a concave lens, high magnification can be achieved at a short camera length. Even under the condition of a camera length of about 7 m, a magnification higher than 300× was achieved, and a line and space pattern with a pitch of 40 nm was observed at 10 keV. By inserting a knife edge at an appropriate position in the optical system, a phase-contrast image can be easily obtained, which is useful for soft-tissue observation of biological samples.

Demonstration tests of the alignment of Fresnel zone plate focusing optics using a full-field x-ray microscope and microbeam x-ray diffraction measurements combined with the full-field x-ray microscope were performed. It was confirmed that the full-field x-ray microscope enables direct two-dimensional observation of a microbeam with sub-micrometer spatial resolution. This allowed visualization of the misalignment of the focusing optics, resulting in accurate alignment of the optics within a short time. In addition, the microscope could be used to observe the sample as well as the microbeam, which enabled clarification of the position and two-dimensional shape of the microbeam on the sample. This realized a measurement procedure that a 100- μm-size sample was imaged with sub-micrometer spatial resolution, and then, microbeam-use measurements were performed for only the region of interest determined by the microscope, which has been difficult with conventional microbeam applications. The combination of observations by a full-field x-ray microscope and measurements using a microbeam is expected to open a new style of measurement.

Angle-resolved photoemission spectroscopy using a micro-focused beam spot (micro-ARPES) is becoming a powerful tool to elucidate key electronic states of exotic quantum materials. We have developed a versatile micro-ARPES system based on synchrotron radiation beam focused with a Kirkpatrick-Baez mirror optics. The mirrors are monolithically installed on a stage, which is driven with five-axes motion, and are vibrationally separated from the ARPES measurement system. Spatial mapping of the Auphotolithography pattern on Si signifies the beam spot size of 10 $\mu$m (horizontal) x 12 $\mu$m (vertical) at the sample position, which is well suited to resolve the fine structure in local electronic states. Utilization of the micro beam and the high precision sample motion system enables the accurate spatially resolved band-structure mapping, as demonstrated by the observation of a small band anomaly associated with tiny sample bending near the edge of a cleaved topological insulator single crystal., Comment: 21 pages, 8 figures

International audience; On April 23rd, 2019, the Aguas Zarcas meteorite fall occurred in Costa Rica. Because the meteorite was quickly recovered, it contains valuable extraterrestrial materials that have not been contaminated by terrestrial processes. Our X-ray computed tomography (XCT) and scanning electron microscopy (SEM) results on various pre-rain fragments from earlier work (Kerraouch et al., 2020; 2021) revealed several distinct lithologies: Two distinct metal-rich lithologies (Met-1 and Met-2), a CM1/2 lithology, a C1 lithology, and a brecciated CM2 lithology consisting of different petrologic types. Here, we further examined these lithologies in the brecciated Aguas Zarcas meteorite and report new detailed mineralogical, chemical, isotopic, and organic matter characteristics. In addition to petrographic differences, the lithologies also display different chemical and isotopic compositions. The variations in their bulk oxygen isotopic compositions indicate that the various lithologies formed in different environments and/or under diverse conditions (e.g., water/rock ratios). Each lithology experienced a different hydration period during its evolution. Together, this suggests that multiple precursor parent bodies may have been involved in these processes of impact brecciation, mixing, and re-assembly. The Cr and Ti isotopic data for both the CM1/2 and Met-1 lithology are consistent with those of other CM chondrites, even though Met-1 displays a significantly lower ε50Ti isotopic composition that may be attributable to sample heterogeneities on the bulk meteorite scale and may reflect variable abundances of refractory phases in the different lithologies of Aguas Zarcas. Finally, examination of the organic matter of the various lithologies also suggests no strong evidence of thermal events, but a short-term heating cannot completely be excluded. Raman parameters indicate that the peak temperature has been lower than that for Yamato-793321 (CM2, ∼400 °C). Considering the new information presented in this study, we now better understand the origin and formation history of the Aguas Zarcas daughter body.

An azimuthal-rotation sample holder, with improvements in the rotation-angle accuracy and rotation-axes displacement during azimuthal rotation, was developed for molecular-orientation analysis using scanning transmission X-ray microscopy., In this study, an azimuthal-rotation sample holder compatible with scanning transmission X-ray microscopy was developed. This holder exhibits improvement in the accuracy of rotation angles and reduces the displacement of the rotation axes during azimuthal rotation by using a crossed roller bearing. To evaluate the performance of the holder, the authors investigated the dependence of the optical density around the C K-edge absorption of π-orbital-oriented domains in natural spherical graphite on the rotational angle by using linearly horizontally and vertically polarized undulator radiation. Based on the dependence of the optical density ratio between C 1s → π* and 1s → σ* excitation on the polarization angle of the X-rays, the average two-dimensional orientation angle of the π orbital in each position in a natural spherical graphite sample was visualized.

Beamline 13 of the Photon Factory has been in operation since 2010 as a vacuum ultraviolet and soft X-ray undulator beamline for X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and angle-resolved photoelectron spectroscopy (ARPES) experiments. The beamline and the end-station at branch B have been recently upgraded, enabling microscopic XPS, XAS, and ARPES measurements to be performed. In 2015, a planar undulator insertion device was replaced with an APPLE-II (advanced planar polarized light emitter II) undulator. This replacement allows use of linear, circular, and elliptical polarized light between 48 and 2000 eV with photon intensities of 109–1013 photons s−1. For microscopic measurements, a toroidal post-mirror was renewed to have more focused beam with profile sizes of 78 µm (horizontal) × 15 µm (vertical) and 84 µm × 11 µm at photon energies of 100 and 400 eV, respectively. A high-precision sample manipulator composed of an XYZ translator, a rotary feedthrough, and a newly developed goniometer, which is essential for microscopic measurements, has been used to control a sample specimen in six degrees of freedom, i.e. translation in the X, Y, and Z directions and rotation in the polar, azimuthal, and tilt directions. To demonstrate the performance of the focused beams, one- and two-dimensional XPS and XAS scan measurements of a copper grid have been performed. It was indicated from analysis of XPS and XAS intensity maps that the actual spatial resolution can be determined by the beam size.

The phase transformation of noncrystalline solids is quite different from that of crystalline solids. To gain a better understanding, a kinetic model for pressure-induced phase transformation of noncrystalline solids is constructed by formulating activation- and free-energy distributions. The model is applied to permanent densification of $\mathrm{Si}{\mathrm{O}}_{2}$ glass, which occurs as a result of a transformation in the network structure. The model is found to be effective in reproducing interesting behavior, including the existence of an infinite number of intermediate states, each of which has a distinct compression curve like a phase, and a halt in the transformation before completion even at sufficiently high temperatures.

The 11th Symposium on Polar Science/Ordinary sessions: [OA] Antarctic meteorites, Thu. 3 Dec.

At a soft X-ray beamline with an undulator source, significant heat generation at the first-mirror chamber and light emission at the viewport were found, which can be explained by photoelectrons from the mirror. The chamber temperature increases up to approximately 50°C over a period of several hours. A photoelectron shield consisting of thin copper plates not only prevents the heat generation and light emission but also improves the pressure of the vacuum chamber, if a voltage of a few tens of V is applied to the shield. The total electron yield of the shield reached as much as 58 mA under high heat-load conditions, indicating the emission of numerous photoelectrons from the first mirror. Heat-balance analyses suggest that approximately 30% or more of the heat load on the first mirror is transferred to the surroundings.

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Silica glass is an optically homogeneous material with many practical applications. Unlike crystalline materials, it remains optically homogeneous during transformations. However, high-pressure in situ small-angle x-ray-scattering measurements indicate an increase in the scattering intensity during the transformation in short-range order between fourfold-coordinated and sixfold-coordinated amorphous polymorphs, providing strong evidence for heterogeneity. Detailed analyses suggest that silica glass consists of optically invisible subnanometer-scale domains for the two amorphous polymorphs and boundary region between them. The boundary region, which likely has an intermediate structure, is comparable in size to the domains, and works as a buffer to prevent the glass from cracking during the transformation. The transformation is more drastic and the domains are more distinct upon decompression than compression.

Recent advances in techniques for high-pressure and high-temperature experiments enable us to measure the velocity of sound in liquid Fe alloys. However, reported velocities in liquid Fe–S differ among research groups (e.g., by >10% at 5 GPa), even when similar methods are used (i.e., the ultrasonic pulse–echo overlap method combined with a large volume press). To identify the causes of the discrepancies, we reanalyzed previous data and conducted additional sound velocity measurements for liquid Fe–S at 2–7 GPa, and evaluated the potential error sources. We found that the discrepancy cannot be explained by errors in the sound velocity measurements themselves, but by inaccuracies in determining the temperature, pressure, and chemical composition in each experiment. Of particular note are the significant errors introduced when determining pressures from the unit-cell volume of MgO, which is a temperature-sensitive pressure standard, using inaccurate temperatures. To solve the problem, we additionally used h-BN as a pressure standard, which is less sensitive to temperature. The pressure dependence of the sound velocity became smaller than that of the original data because of the revised pressure values. Our best estimate for the seismic velocity of the Moon’s liquid outer core is 4.0 ± 0.1 km/s, given a chemical composition Fe 83 S 17 .

The structure of hydrous amorphous SiO2 is fundamental in order to investigate the effects of water on the physicochemical properties of oxide glasses and magma. The hydrous SiO2 glass with 13 wt.% D2O was synthesized under high-pressure and high-temperature conditions and its structure was investigated by small angle X-ray scattering, X-ray diffraction, and neutron diffraction experiments at pressures of up to 10 GPa and room temperature. This hydrous glass is separated into two phases: a major phase rich in SiO2 and a minor phase rich in D2O molecules distributed as small domains with dimensions of less than 100 &Aring, Medium-range order of the hydrous glass shrinks compared to the anhydrous SiO2 glass by disruption of SiO4 linkage due to the formation of Si&ndash, OD deuterioxyl, while the response of its structure to pressure is almost the same as that of the anhydrous SiO2 glass. Most of D2O molecules are in the small domains and hardly penetrate into the void space in the ring consisting of SiO4 tetrahedra.

A SnI4 molecule lowers its symmetry from T d to [Formula: see text] on the liquid-liquid transition. Because it is possible to lower the molecular symmetry without violating the crystalline symmetry, it is worth examining whether the deformation occurs in the crystalline phase field. Extended x-ray absorption fine structure (EXAFS) measurements on the crystalline state were carried out to investigate the change in the environment around a Sn atom at high pressures and temperatures. We could not find clear evidence on the symmetry change of molecules even close to the melting points, where the melting curve becomes abnormally flat against pressure. Indeed, no inconsistency was found when we assumed that the coordination number of a Sn atom remains unchanged in the temperature and pressure range examined. The situation remains true when the system entered the high-pressure crystalline phase on compression. We can propose a consistent scenario as to the structural change on the phase transformation. The incompressibility of a SnI4 molecule could be suitably quantified. The procedure enabled us to conclude the molecule is more than an order of magnitude incompressible than the lattice.

We investigated the stability of the liquid phase of a series of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Cnmim][TFSI]) homologues with different alkyl chain lengths for 3 ≤ n ≤ 10 at room temperature. We found that all [Cnmim][TFSI] samples (n = 3–10) formed a glassy state when pressure was applied. Intriguingly, the glass transition pressure (pg) slightly increases up to n = 5, reaches a plateau at n ≧ 8, and increases again at n = 10. This is completely different from the high-pressure glass formation of [Cnmim][BF4], where the pg decreases as n increases. We discussed the local structural changes occurring in [Cnmim][TFSI] in view of the conformational changes of the cation and anion, and small-angle X-ray scattering data. It seems that [Cnmim][TFSI] is resistant to external pressure and retains its local liquid structure by conformational adjustments of the cation and anion.