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木村 ゆうき
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Achiral Metastable Crystals of Sodium Chlorate Forming Prior to Chiral Crystals in Solution Growth. Hiromasa Niinomi, Tomoya Yamazaki, Shunta Harada, Toru Ujihara, Hitoshi Miura, Yuki Kimura, Takahiro Kuribayashi, Makio Uwaha, Katsuo Tsukamoto. Chiral symmetry breaking in NaClO3 crystallization from an aqueous solution with perturbations has been of great interest. To understand the mechanism, several models focusing on the early stage of the crystallization have been proposed.
However, they are ambiguous because the early stage has been barely explored directly. Here, we investigate the early stages of the crystallization process driven by droplet evaporation using a combination of direct in situ microscopic observations and cryogenic single-crystal XRD experiments. We advocate further assessment of the achiral crystal and a new pathway for the formation of chiral crystals via crystalline phase transition from achiral Phase III.
Cathodoluminescence microscopy and spectroscopy of forsterite from Kaba meteorite: An application to the study of hydrothermal alteration of parent body. Arnold Gucsik, Taro Endo, Hirotsugu Nishido, Kiyotaka Ninagawa, Masahiro Kayama, Szaniszlo Berczi, Szabolcs Nagy, Peter Abraham, Yuki Kimura, Hitoshi Miura, Ildiko Gyollai, Irakli Simonia, Peter Rozsa, Jozsef Posta, Daniel Apai, Krisztian Mihalyi, Mihaly Nagy, Ulrich Ott.
Highly forsteritic olivine Fo: CL spectra of red luminescent forsterite grains have two broad emission bands at approximately nm impurity center of divalent Mn ions in the red region and above nm trivalent Cr ions in the red-IR region. The cores of the grains show CL blue luminescence giving a characteristic broad band emission at nm, also associated with minor red emissions related to Mn and Cr ions.
CL color variation of Kaba forsterite is attributed to structural defects. Electron probe microanalyzer EPMA analysis shows concentrations of Ca, Al, and Ti in the center of the forsterite grain. The migration of diffusible ions of Mn, Cr, and Fe to the rim of the Kaba meteoritic forsterite was controlled by the hydrothermal alteration at relatively low temperature estimated at about degrees C , while Ca and Al ions might still lie in the core.
A very unusual phase of FeO wustite was also observed, which may be a terrestrial alteration product of FeNi-metal. Vortex magnetic structure in framboidal magnetite reveals existence of water droplets in an ancient asteroid. Yuki Kimura, Takeshi Sato, Norihiro Nakamura, Jun Nozawa, Tomoki Nakamura, Katsuo Tsukamoto, Kazuo Yamamoto. The majority of water has vanished from modern meteorites, yet there remain signatures of water on ancient asteroids.
How and when water disappeared from the asteroids is important, because the final fluid-concentrated chemical species played critical roles in the early evolution of organics and in the final minerals in meteorites. Here we show evidence of vestigial traces of water based on a nanometre-scale palaeomagnetic method, applying electron holography to the framboids in the Tagish Lake meteorite.
The framboids are colloidal crystals composed of three-dimensionally ordered magnetite nanoparticles and therefore are only able to form against the repulsive force induced by the surface charge of the magnetite as a water droplet parches in microgravity. We demonstrate that the magnetites have a flux closure vortex structure, a unique magnetic configuration in nature that permits the formation of colloidal crystals just before exhaustion of water from a local system within a hydrous asteroid.
MET Another Tagish Lake-type Carbonaceous Chondrite from Antarctica. Acceleration and inhibition effects of phosphate on phase transformation of amorphous calcium carbonate into vaterite. Phase transformation of amorphous calcium carbonate ACC into vaterite and its subsequent stability was investigated at a constant pH similar to 8.
Solutions containing the same concentrations of CaCl2, Na2CO3, and tris hydroxymethyl aminomethane buffer and various concentrations of PO4 The change in the Ca-ion concentration over time, which served as a guide for phase transformation of ACC into crystalline phases, was measured in relation to the PO4 concentration.
The starting time of phase transformation was at the minimum point when the concentration was similar to mu M. Vaterite spherulites consisting of needle-like crystals 0.
In contrast, the starting time of phase transformation increased exponentially with the PO4 concentration when it was higher than 5 mu M. The vaterite spherulites and calcite crystals co-precipitated, and both polymorphs grew over time. We investigated the kinetics of vaterite formation in the presence of PO4 and derived an advanced concept for cluster-based phase transformation. This investigation showed that the appearance and stability of calcium carbonate polymorphs is easily controlled by adjusting the PO4 concentration.
THE MECHANISM OF SURFACE DIFFUSION OF H AND D ATOMS ON AMORPHOUS SOLID WATER: EXISTENCE OF VARIOUS POTENTIAL SITES. Tetsuya Hama, Kazuaki Kuwahata, Naoki Watanabe, Akira Kouchi, Yuki Kimura, Takeshi Chigai, Valerio Pirronello. To understand elementary processes leading to H-2 formation, and the hydrogenation and deuteration reactions of adsorbed species on dust grains in dense clouds, we experimentally investigated the diffusion of atomic hydrogen and deuterium on amorphous solidwater ASW at temperatures of K.
The present study pictured the outline of H-2 formation on cosmic ice dust at low temperatures: H atoms landing on the dust will diffuse rapidly at the abundant shallow and middle sites on ASW, and finally become trapped at deep sites. The H atoms that arrive next recombine with such trapped H atoms to yield H-2 molecules.
The small isotopic difference between the diffusion of H and D atoms on ASW indicates that the diffusion mechanism can be explained by thermal hopping, at least at middle-potential sites. Direct Observation of the Homogeneous Nucleation of Manganese in the Vapor Phase and Determination of Surface Free Energy and Sticking Coefficient. We examined the homogeneous condensation of thermally evaporated manganese vapor in an atmosphere of argon gas and determined the temperature and concentration during homogeneous nucleation in the vapor phase by using a Mach-Zehnder type interferometer.
Condensation occurred at K below the equilibrium temperature and the degree of supersaturation was as high as similar to 5 x 10 4.
The nucleation theories predict that the critical nucleus contains only three and six atoms for CNT and SP, respectively, which are fewer than the number of atoms in a unit cell of Mn.
This suggests that the polymorphic form of manganese is decided during particle growth rather than during nucleation from the vapor phase. Cathodoluminescence microcharacterization of forsterite in the chondrule experimentally grown under super cooling. Cathodoluminescence CL of laboratory forsterite chondrules has been characterized to clarify the formation process of chondrules and related mechanism of the crystal growth in a supercooled melt.
Color CL image of the experimentally grown forsterite exhibits significant blue luminescence in the main branches of the interior structure of lab-chondrule, which reflects to the anisotropy of crystallization.
A new CL band centered at nm 2. Morphological evolution of precipitates during transformation of amorphous calcium phosphate into octacalcium phosphate in relation to role of intermediate phase.
Nucleation of amorphous calcium phosphate ACP and its phase transformation with a decrease in solution pH were investigated at a constant temperature of 32 degrees C. A gel-like solution structure formed immediately after mixing and contained a small amount of sea-urchin-like ACP spherulites mu m in size. These spherulites consisted of 1. They first transformed into beta-tri calcium phosphate-like material called “pseudo beta-TCP” and then into single crystals of octacalcium phosphate OCP without dissolution.
The flexible needles in the spherulites changed into blade springs, then into flexible plates, and finally into rigid plates during the transformation. The OCP structure appeared in the pseudo beta-TCP plates and gradually substituted for the beta-TCP structure over time. The macroscopic spherulite morphology of the initial ACP remained unchanged during the phase transformation, suggesting that OCP is a pseudomorph of ACP.
This feature was observed only when the ACP spherulites formed in the initial solution. Fiber-like aggregates consisting of beta-TCP single crystals nucleated around the ACP spherical particles and grew over time. They survived until the final stage of the reaction, and OCP polycrystals formed in the mixture of beta-TCP and ACP spheres.
The OCP polycrystals gradually substituted for the ACP spheres without phase transformation of beta-TCP into OCP. Magnetite 3D Colloidal Crystals Formed in the Early Solar System 4. Jun Nozawa, Katsuo Tsukamoto, Willem van Enckevort, Tomoki Nakamura, Yuki Kimura, Hitoshi Miura, Hisao Satoh, Ken Nagashima, Makoto Konoto. Three-dimensional colloidal crystals made of ferromagnetic particles, such as magnetite Fe 3 O 4 , cannot be synthesized in principle because of the strong attractive magnetic interaction.
However, we discovered colloidal crystals composed of polyhedral magnetite nanocrystallites of uniform size in the range of a few hundred nanometers in the Tagish Lake meteorite. Those colloidal crystals were formed 4. We also hypothesize that each particle has a flux-closed magnetic domain structure, which reduces the interparticle magnetic force significantly.
Interferometric in-situ observation during nucleation and growth of WO3 nanocrystals in vapor phase. To investigate the homogeneous nucleation and growth process of nanoparticles in vapor phase, interferometric observation was attempted for the first time to the gas evaporation method, which has been a commonly accepted physical production method of nanoparticles.
Tungsten oxide was evaporated by electrical heating of a tungsten wire in a mixture gas of Ar and O WO3 nanoparticles were formed via homogeneous nucleation and growth during a gas cools following a thermal convection produced by the evaporation source. The degree of supersaturation for nucleation was extremely high, 6.
Surface free energy of WO3 at K was calculated based on the classical nucleation theory and was 1. A part of the difference between actual formation rate of produced nanoparticles, which were determined based on a transmission electron microscope, and calculated values based on the classical nucleation theory were well explained if we adopt the idea of coalescence growth.
Synthesis of Stacked-Cup Carbon Nanotubes in a Metal Free Low Temperature System. Yuki Kimura, Joseph A. Nuth, Natasha M. Johnson, Kevin D. Farmer, Kenneth P. Roberts, Syed R. Stacked-cup carbon nanotubes were formed by either Fischer-Tropsch type or Haber-Bosch type reactions in a metal free system. Graphite particles were used as the catalyst. The samples were heated at degrees C in a gas mixture of CO 75 Torr, N-2 75 Torr and H-2 Torr for three days.
Transmission electron microscope analysis of the catalyst surface at the completion of the experiment recognized the growth of nanotubes. They were nm in diameter and similar to 1 mu m in length. They had a hollow channel of nm in the center. The nanotubes may have grown on graphite surfaces by the CO disproportionation reaction and the surface tension of the carbon nucleus may have determined the diameter. Although, generally, the diameter of a carbon nanotube depends on the size of the catalytic particles, the diameter of the nanotubes on graphite particles was independent of the particle size and significantly confined within a narrow range compared with that produced using catalytic amorphous iron-silicate nanoparticles.
Therefore, they must have an unknown formation process that is different than the generally accepted mechanism.
Laboratory annealing experiments of refractory silicate grain analogs using differential scanning calorimetry. Exothermic reactions during the annealing of laboratory synthesized amorphous magnesium-bearing silicate particles used as grain analogs of cosmic dust were detected by differential scanning calorimetry DSC in air.
With infrared spectroscopy and transmission electron microscopy, we show that cosmic dust could possibly undergo fusion to larger particles, with oxidation of magnesium silicide and crystallization of forsterite as exothermic reactions in the early solar system.
The reactions begin at approximately , approximately , and approximately K, respectively, and the reaction energies enthalpies are at least , , and During the crystallization of forsterite particles, the spectral evolution of the 10 mu m feature from amorphous to crystalline was observed to begin at lower temperature than the crystallization temperature of K.
Interferometric observation of temperature distributions in the smoke experiment. Physicochemical processes of atomic hydrogen on amorphous solid water at very low temperatures.
THE FORMATION OF GRAPHITE WHISKERS IN THE PRIMITIVE SOLAR NEBULA. It has been suggested that carbonaceous grains are efficiently destroyed in the interstellar medium and must either reform in situ at very low pressures and temperatures or in an alternative environment more conducive to grain growth.
Graphite whiskers have been discovered associated with high-temperature phases in meteorites such as calcium aluminum inclusions and chondrules, and it has been suggested that the expulsion of such material from protostellar nebulae could significantly affect the optical properties of the average interstellar grain population. We have experimentally studied the potential for Fischer-Tropsch and Haber-Bosch type reactions to produce organic materials in protostellar systems from the abundant H 2 , CO, and N 2 reacting on the surfaces of available silicate grains.
When graphite grains are repeatedly exposed to H 2 , CO, and N 2 at K abundant graphite whiskers are observed to form on or from the surfaces of the graphite grains. In a dense, turbulent nebula, such extended whiskers are very likely to be broken off, and fragments could be ejected either in polar jets or by photon pressure after transport to the outer reaches of the nebula.
Formation of polycyclic aromatic hydrocarbon grains using anthracene and their stability under UV irradiation. It has been known for sonic time that the properties of a material are changed in nanometer size. Since it is nontrivial that polycyclic aromatic hydrocarbon PAH grains at the nanometer scale show similar properties with that of macroscopic scale, PAH grains were synthesized by a gas evaporation method and were analyzed using a transmission electron microscope and their UV-Vis and mid-IR spectra were Measured.
Results from these experiments showed that condensed anthracene grains from the gas phase had a planar form and showed similar infrared peaks compared to anthracene molecules, but With somewhat wider bands and different relative intensities.
Sonic new features were also observed. The anthracene molecules formed photodimer ill their grain and showed different infrared features after UV irradiation. This Would be the first report concerning nanometer-sized PAH grains. Direct measurements of hydrogen atom diffusion and the spin temperature of nascent H2 molecule on amorphous solid water. Synthesis of stacked-cup carbon nanotubes in a metal free low temperature system.
AFM study on surface nanotopography of matrix olivines in Allende carbonaceous chondrite. Jun Nozawa, Katsuo Tsukamoto, Hidekazu Kobatake, Junya Yamada, Hisao Satoh, Ken Nagashima, Hitoshi Miura, Yuki Kimura. By means of nanoscale surface observation, we have proposed a new approach for investigating fine crystals of cosmic materials to reveal their origin and growth conditions.
Several different morphologies of polyhedral fine olivines with faceted faces have been found in Allende carbonaceous chondrite 4. In the present work, molecular level topography of the faceted matrix olivine by Atomic Force Microscopy AFM has Successfully been performed, The matrix olivine found to have preserved growth step pattern on its surface even though quite long time has passed since they formed in the early Solar System. The Surface pattern Suggests that the faceted matrix olivine could have been condensed from the gas phase, and possibly that these olivine crystals had continued to grow under a rapid cooling condition 0.
The estimated cooling rate agrees well with predictions based on hypothetical rapid heating and cooling events such as shock wave heating. Analogs of organic hollow globules, which have been found in carbonaceous chondrite meteorites and interplanetary dust particles, were synthesized in our laboratory from benzene and anthracene using plasma. Our results suggest that organic globules could be made from aromatic rings in circumstellar envelopes around evolved stars.
This experimental result suggests that organic globules are possibly the final products in the evolution of carbonaceous matter from acetylene and benzene to polycyclic aromatic hydrocarbons in ejecta gas from evolved stars. Laboratory experiments suggest that magnesium silicide Mg 2 Si grains could be produced in the hydrogen dominant gas outflow from evolved stars in addition to amorphous oxide minerals. If the magnesium silicide grains were incorporated into the primitive solar nebula, the magnesium silicide would easily become forsterite Mg 2 SiO 4 by oxidation as it reacted with the relatively oxygen-rich, solar composition gas.
This hypothesis can explain the existence of abundant forsterite grains with solar oxygen composition in meteorites, i. In addition, if a significant fraction of the solar forsterite is derived from magnesium silicide, it could explain the apparent low abundance of presolar forsterite.
Furthermore, the lower degree of crystallinity observed in silicates formed in outflows of lower mass-loss-rate stars might be caused by the formation of magnesium silicide in this relatively hydrogen-rich environment. 材料あれこれ〔その他〕 46億年昔の宇宙空間での結晶化. Origin of organic globules in meteorites: Laboratory simulation using aromatic hydrocarbons.
The American Astronomical Society. Experimental demonstration of condensation of Mg-bearing silicate grains around evolved stars. Mg-bearing silicate grains were produced directly from the vapor phase from magnesium and silicon oxide in a mixed atmosphere of Ar and O-2 in the laboratory. It was found that the crystallinity, which was deduced from the shape of the 10 mu m feature, of the grains depends on the ratio of magnesium to silicon oxide in the vapor phase.
The experimental result suggests that the crystallinity of circumstellar silicates could be determined by the balance between heat generation by magnesium oxidation and heat dissipation due to radiation. In this situation, later annealing of the silicate fraction or the use of a warm substrate for condensation of crystalline silicate is unnecessary. Crystalline silicates found in young stars are also able to be produced following our hypothesis after simultaneous evaporation of silicates and ices during energetic shocks in protostellar nebulae.
Morphological alteration and structure of ZnO particles produced in electric field. Chihiro Kaito, Yasuhiko Kinuta, Hitoshi Suzuki, Syunsuke Adachi, Akihito Kumamoto, Yoshio Saito, Yuki Kimura. The apparent morphological difference between ZnO particles with and without an electric field applied during the growth process was elucidated by high-resolution transmission electron microscopy.
The ZnO smoke produced immediately below the electric field by burning zinc in a gas mixture of O-2, and Ar, curved towards a negative plate. The typical tetrapod- or needle-shaped ZnO particles were seldom observed in the electric field; spherical particles were predominantly produced. Some of these spherical particles were composed of multiply twinned particles with an antiphase boundary.
The growth of these multiply twinned particles was due to an increment in the ionicity in the crystallographic polar direction of ZnO bonding induced by the applied electric field. POSSIBLE DRIVING FORCE BEHIND FORMATION OF COSMIC CARBYNE CRYSTALS.
Regarding the formation of cosmic dust, condensation and thermal alteration have been considered as clues to the formation mechanism and environments experienced by dust. Unfortunately, however, the formation mechanisms of many types of dust found in meteorites are still unidentified. Carbyne crystals found in carbonaceous meteorites are also one type of enigmatic mineral dust. We show a new route for the formation of cosmic carbyne crystals via synchrotron radiation as a more favorable driving force than condensation from hot gas.
Carbyne crystals were produced under a coronal photon flux corresponding to 32 days at a heliocentric distance of 5 AU, which corresponds to the orbit of Jupiter, with respect to the young Sun. The novel method of synthesizing carbyne crystals will be useful for understanding the material evolution of carbonaceous dust. Direct observation of MoO 2 crystal growth from amorphous MoO 3 film. The formation process of MoO 2 crystal from amorphous MoO 3 film has been imaged by in situ observation with a transmission electron microscope.
Selective growth of flower-shaped MoO 2 crystals by heating above K in vacuum was directly observed. Since the MoO 2 crystal has metallic conductivity of the order of indium oxide film containing tin ITO film , the thin film growth of the MoO 2 phase has been discussed on the basis of a new substitute for ITO film.
Structural Alterations of Carbon Particles in Saturated Water Vapor. Chihiro Kaito, Masayuki Shintaku, Ryuta Sakao, Akihito Kumamoto, Midori Saito, Yuki Kimura, Shinsuke Ohyagi, Shigeru Morikawa, Hiroshi Suzuki. High-resolution transmission electron microscopy HRTEM of carbon particles has been carried out at 80 degrees C in saturated water vapor, to evaluate any structural alterations. Amorphous particles or microcrystallites of carbon based on the graphitic structure were altered to more stable graphitic structures such as ribbons or onion-like structures.
The stable graphitic structure was altered again to the amorphous structure. Results are interpreted in terms of the oxidation of carbon particles in air.
The differences in alterations among carbon particles, Pt clusters on carbon particles, and Pt clusters in carbon particles are presented on the basis of HRTEM images. Crystallinity of Mg-bearing silicate grains due to condensation or thermal evolution.
Characteristic low-temperature crystallization of amorphous Mg-bearing silicate grains under electron irradiation. Amorphous Mg-bearing silicate grains, which were produced by the coalescence between MgO and SiOx smoke particles, were crystallized to forsterite Mg2SiO4 by electron-beam irradiation in a transmission electron microscope at room temperature.
The crystallization induced by electron beams was accelerated by the presence of CH4 adsorbed on the surface and incorporated interior of the grains. This experimental result implies the possibility of low-temperature crystallization in a silicate carbon star. In the case of binary stars, since the materials that flow from the stars stationarily exist around the star, the formed amorphous silicate grains will be irradiated by electrons from the star for a long duration.
As a result, a significant amount of crystalline silicates can be produced. Production of refractory-metal ultrafine particles by gas evaporation method and their surface oxide layer. Generally, molybdenum, tungsten or tantalum is used as the evaporation source of many kinds of materials because of their high melting points and reasonably low vapor pressures.
Therefore, the production of ultrafine particles of molybdenum, tungsten and tantalum has not been achieved by gas evaporation method. In this paper, it is shown that ultrafine particles of molybdenum, tungsten and tantalum were produced by a modified gas evaporation method. Transmission electron microscope observations show that the produced particles had a bcc structure with a size of less than 50 nm.
Then, the thicknesses and the structures of the natural oxide layers were determined. Metallic particles develop an oxide layer on their surface and produce composite material automatically.
Therefore, when metallic particles are used industrially or are treated in theoretical calculation studies, in view of realistic materials, the effect of the natural oxide layer must be considered. By the use of this modified gas evaporation method, ultrafine particles of many kinds of refractory materials will be produced.
A refractory Ca-SiO-H 2 -O 2 vapor condensation experiment with implications for calciosilica dust transforming to silicate and carbonate minerals. Condensates produced in a laboratory condensation experiment of a refractory Ca-SiO-H 2 -O 2 vapor define four specific and predictable deep metastable eutectic calciosilica compositions.
The condensed nanograins are amorphous solids, including those with the stoichiometric CaSiO 3 pyroxene composition. In evolving dust-condensing astronomical environments they will be highly suitable precursors for thermally supported, dust-aging reactions whereby the condensates form more complex refractory silicates, e. This kinetically controlled condensation experiment shows how the aging of amorphous refractory.
condensates could produce the same minerals that are thought to require high-temperature equilibrium condensation. We submit that evidence for this thermal annealing of dust will be the astronomical detection of silica amorphous or crystalline that is the common, predicted, by-product of most of these reactions.
Possible Driving Force behind Formation of Cosmic Carbyne Crystals. In situ observation of structural alteration process of filmy quenched carbonaceous composite. Structural alteration of nanostructure carbon particles carrying Pt clusters in H-2 and O-2 gases. Chihiro Kaito, Ryoichi Ono, Ryuta Sakao, Akihito Kuniamoto, Midori Saito, Yuki Kimura, Shinsuke Ohyagi.
The effects of H-2 and O-2 gases on the typical fuel cell catalyst of Pt clusters on carbon particles Pt on Q were examined using a special side-entry sample holder for high-resolution transmission electron microscopy, The holder can be used to transfer the specimen without exposure to air. The effects of H-2 and O-2 were detected after the specimen was exposed to the gases at 60 degrees C for 15 h.
The predominant effect of H-2 was the coagulation of the Pt clusters. The effect of O-2 was to alter the structure of the carbon particles by oxidation. explain how cometary silicates crystallize yet still preserve volatile interstellar ices in their parent comets, we experimentally demonstrate the possibility of chemical-reaction-driven crystallization, which is called nonthermal crystallization, using laboratory-synthesized amorphous Mg-bearing silicate grains.
Analog silicate grains similar to nm in diameter covered with a carbonaceous layer consisting of amorphous carbon, CH 4, and other organics to a thickness of similar to nm were used as models. The analog silicate grains crystallized via the direct flow of surface reaction energy, which is produced by the graphitization of the carbonaceous layer due to oxidation at room temperature in air, into the silicates.
The experimental results imply that amorphous silicates are transformed into crystalline silicates as the grains leave the comet’s surface, rather than as the comet was accreted 4. Thus, primordial ices and amorphous silicate grains are predicted to reside in most comets until they approach the Sun. What is the driving force to form refractory oxide grains?
Silicate spectra depend on their formation environment. We discuss room-temperature condensation experiments using either an electrical discharge or ultraviolet radiation to initiate gas-phase reactions resulting in silicate smokes.
This formation process could represent processes occurring in low-density environments, because it is possible that the gases, which can condense at higher temperatures, remain after it cools, e. In these environments, many condensates could be formed simultaneously. However, in the case of our iron silicate experiments, many of the smoke particles are iron silicate with a uniform composition that reflects the composition of the ambient gas atmosphere where they were produced.
In these experiments, smoke particles of other materials such as iron oxide and silica were not formed. In the case of our Si-O experiments, hydro-silicate smoke particles are produced together with anhydrous silicate particles directly from the gas phase without later hydro alteration.
The infrared spectra of these silicate particles show a very strong We believe that finding the driving force for grain growth under a wide range of environmental conditions is important if we are to understand grain formation, because silicate grains, which formed in a plasma field or under UV irradiation, show different compositions, structures, shapes, and spectra from thermally condensed grains.
Non-mass-dependent oxygen isotopic fractionation in smokes produced in an electrical discharge. The smokes were formed at the Goddard Space Flight Center GSFC at total pressures of just under Torr in an electrical discharge powered by a Tesla coil, were collected from the surfaces of the copper electrodes after each experiment and sent to the University of California at San Diego UCSD for oxygen isotopic analysis.
Transmission electron microscopy studies of the smokes show that they grew in the gas phase rather than on the surfaces of the electrodes. We hypothesize at least two types of fractionation processes occurred during formation of the solids: a mass-dependent process that made isotopically lighter oxides compared to our initial oxygen gas composition followed by a mass-independent process that produced oxides enriched in 17 O and 18 O.
More typical displacements are parts per thousand above the equilibrium fractionation line. The chemical reaction mechanisms that yield these smokes are still under investigation. 期待される結晶成長 原始太陽系における物質進化に関わる結晶成長. Direct observation of the crystallization of carbon-coated amorphous Mg-bearing silicate grains. Chihiro Kaito, Shinichi Sasaki, Yu Miyazaki, Akihito Kumamoto, Mami Kurumada, Kaori Yokoyama, Midori Saito, Yuki Kimura, Hitoshi Suzuki.
The crystallization of amorphous Mg-bearing silicate grains into Mg2SiO4 crystal covered with a thin carbon layer was directly observed by in-situ transmission electron microscopy.
The graphitization energy of the surface amorphous carbon layer with the mean thickness of 10 nm accelerated the crystallization of the central amorphous Mg-bearing silicate grain of nm order. Sample results for crystallization at room temperature are presented. New method of producing titanium carbide, monoxide, and dioxide grains in laboratory. By making a carbon rod covered with Ti on the surface without exposure to air, TiC grains less than 10nm in diameter were predominantly produced.
The infrared spectra of TiO2, TiO, and TiC were measured. An absorption feature attributed to TiO phase in oxidized TiC grains showed a characteristic peak at Variety of refractory oxide grains depend on formation environments. Demonstration of crystal forsterite and stall state grain formations. Influence of plasma on formation of crystalline Fe2SiO4 grains.
The production of Fe2SiO4 fayalite crystalline grains was performed by two processes, namely, grain formation in a plasma field by evaporating a mixture powder of Fe and SiO and heat treatment of the product collected on the radio-frequency RF electrode side. By heating at degrees C, in addition to the formation of Fe2SiO4 crystal grains, the FeO phase appeared. The doping effect of excited oxygen in a plasma field into the Fe small grains may be the trigger on the formation of fayalite through the FeO phase formation.
The present experimental result suggests that the probability Of Fe2SiO4 grain formation in space is low. c Published by Elsevier Ltd. Laboratory analogy of crystalline enstatite grain formation in plasma field. Crystalline enstatite MgSiO3 grains were produced by the simultaneous evaporation of SiO grains and Mg vapor in a plasma field.
The MgSiO3 grains were spherical or needlelike. The necessity of a plasma field in astromineralogy is suggested in the present study. Formation of TiC core-graphitic mantle grains from CO gas. We demonstrate a new formation route for TiC core-graphitic mantle spherules that does not require carbon-atom addition and the very long time scales associated with such growth Bernatowicz et al.
Carbonaceous materials can be formed from C2H2 and its derivatives, as well as from CO gas. In this paper, we will demonstrate that large-cage-structure carbon particles can be produced from CO gas by the Boudouard reaction. Since the sublimation temperature for such fullerenes is low, the large cages can be deposited onto previously nucleated TiC and produce TiC core-graphitic mantle spherules.
New constraints for the formation conditions and the time scale for the formation of TiC core-graphitic mantle spherules are suggested by the results of this study. In particular, TiC core-graphitic mantle grains that are found in primitive meteorites that have never experienced hydration Could be mantled by fullerenes or carbon nanotubes rather than by graphite.
In situ observations of these grains in primitive anhydrous meteoritic matrix could confirm or refute this prediction and would demonstrate that the graphitic mantle on such grains is a metamorphic feature due to interaction of the presolar fullerenes with water within the meteorite matrix.
Synthesis of Al-Cr decagonal quasicrystal nanoparticles and their temperature of phase transformation to stable crystal phase. The synthesis of Al-Cr single quasicrystal QC nanoparticles of the decagonal phase was achieved by introducing an advanced gas flow evaporation method.
By obtaining Successive electron diffraction patterns for single-QC nanoparticles, the phase transformation temperature of a single-QC nanoparticle was determined to be degrees C.
It was also determined that part of the QC nanoparticle decomposed into hex-AI 8 Cr 5 and Al during the phase transformation. Since the grain growth did not occur during the phase transformation in the present experiment, the inherent phase transformation temperature could be measured.
c Elsevier B. Formation of CaTiO3 crystalline dust in laboratory. Laboratory production of magnesium sulfide grains and their characteristic infrared spectra due to shape. Nanosized MgS grains, which have been considered the origin of the 30 mu m emission feature of carbon-rich evolved objects, were produced from the gas phase using an advanced gas evaporation method.
The far-infrared spectrum of cubic MgS grains showed a characteristic absorption peak at cm -1 On the other hand, when the grains were roundish or network-like, the absorption peak at cm -1 became predominant. The cubic MgS grains were produced by direct nucleation from the gas phase.
In the case of production via a gas-solid reaction, the MgS grains were network-like. Therefore, the formation environments of MgS grains around carbon-rich evolved objects may be predicted from the intensity of and cm -1 bands. Recent measurements of fullerenes and Ti atoms recorded in our laboratory have demonstrated the presence of an infrared feature near 21 mu m. The feature observed has nearly the same shape and position as is observed for one of the most enigmatic features in post-asymptotic giant branch AGB stars.
In our experimental system, large-cage carbon particles, such as large fullerenes, were produced from CO gas by the Boudouard reaction. Large-cage carbon particles intermixed with Ti atoms were produced by the evaporation of a Ti-metal-wrapped carbon electrode in CO gas. The infrared spectra of large fullerenes interacting with Ti atoms show a characteristic feature at Both the laboratory and stellar spectra also show a small but significant peak at Here we propose that the interaction between fullerenes and Ti atoms may be a plausible explanation for the 21 mu m feature seen in some post-AGB stars.
Is the 21 micron feature observed in some post-AGB stars caused by the interaction between Ti atoms and fullerenes? Laboratory production of monophase pyrrhotite grains using solid-solid reaction and their characteristic infrared spectra.
A new method of producing pyrrhotite grains, which are most commonly found in cometary material and interplanetary dust particles, was developed. Pyrrhotite grains in the monophase having a 7C structure were predominately produced using a solid-solid reaction between iron and sulfur grains at room temperature.
The characteristic infrared peaks were observed at , , and cm -1 c Elsevier Inc. Laboratory synthesized calcium oxide and calcium hydroxide grains: A candidate to explain the 6. We demonstrate that CaO and Ca OH 2 are excellent candidates to explain the 6. We discuss the condensation of CaO grains and the potential formation of a Ca OH 2 surface layer. The infrared spectra of these grains are compared with the spectra of 15 young stellar objects.
We note that CaO-rich grains are seen in all meteoritic CAIs calcium-aluminum-rich inclusions and that the 6. Therefore, we consider CaO grains to be a plausible candidate to explain the 6. Formation of carbon nanotubes from mixture film of carbon and titanium.
It was shown that a carbon nanotube was selectively formed from carbon film containing Ti, supported by a standard Mo transmission electron microscopic grid, by heating at degrees C in vacuum.
With heating above degrees C, graphite and rutile crystals of TiO2 predominately appeared. The formation of oxide is due to the supply of oxygen from the Mo grid. The formation mechanism of the carbon nanotubes was discussed on the basis of the heat of combustion due to the oxidation of titanium. The present result will lead to the development of an efficient method of production of carbon nanotubes. Direct observation of thermal alteration of mixed film of Ge and SiO.
The dynamic behavior of a film produced by coevaporation of Ge-SiO was observed in situ using a transmission electron microscope. The film produced had an amorphous structure containing Si, Ge and SiO2. A characteristic change of the film was observed above degrees C. Upon heating at degrees C, in addition to the growth of the SiGe mixed crystal with the diamond structure, the liquidlike mixed phase of SiGe-SiO2 was also produced. The growth process of the liquidlike phase was directly observed in situ.
The growth process of Ge and GeSi nanocrystallites has been elucidated by cooling the mixed film to room temperature. V All rights reserved. Novel routes for diamond formation in interstellar ices and meteoritic parent bodies. We have identified new formation routes of diamond in interstellar clouds and parent bodies of carbonaceous chondrites in laboratory experiments.
The diamond precursor nucleated under UV photolysis of interstellar ice mixtures in molecular clouds and grew with further UV irradiation in diffuse clouds. The present study supports the occurrence of diamonds in interstellar clouds and suggests that diamond is ubiquitous in space.
We also performed experiments on the processes of aqueous alteration and subsequent thermal metamorphism of organic materials formed in molecular clouds, and the results were consistent with the formation of diamonds by this process in the parent bodies of carbonaceous chondrites.
The various characteristics of nanodiamonds in chondrites and interplanetary dust are well explained by these new formation routes. Production of diamond and solid-solution nanoparticles in the carbon-silicon system using radio-frequency plasma.
New rate constants of hydrogenation of CO on H2O-CO ice surfaces. The key route of the formation of solid H2CO and CH3OH on grain surfaces is the hydrogenation reactions.
This route was confirmed recently by experiments carried out by Watanabe and his coworkers in and On the basis of these experimental results, we derive theoretical formulae and determine the rate constants of the formation of H2CO and CH3OH via the hydrogenation of CO molecules in amorphous H2O-CO ice.
In order to reproduce the experimental results, we introduce a new model of the ice called the crack model. We find that the morphology of the ice plays a vital role for the calculations of the rate constants. At temperatures 10 and 15 K, the diffusion constant of hydrogen atoms into the amorphous H2O-CO ice is estimated to be 10 to 10 cm 2 s -1 , which has little effect on the calculations of the rate constant of the surface hydrogenation.
We discuss the deviation of the theoretical results from the experimental ones at late times. Formation of new carbides with diamond structure from carbon film containing transition metal.
New carbide crystallites, which have a solid-solution phase with diamond structure, were formed from amorphous carbon film containing a transition metal such as Fe, Co, Mo or Ti by vacuum heating at degrees C.
The lattice constants for each solid-solution phase have been determined from electron diffraction patterns and high-resolution transmission electron microscope images. The formation of carbon polymorphs has been summarized as being dependent on the heat treatment temperature.
Crystal structure and growth of carbon-silicon mixture film prepared by ion sputtering. The C-Si film was composed of a solid-solution phase of carbon and silicon with a diamond structure. The film showed a higher transparency than a simultaneously evaporated C-Si mixture film. Diamond crystals nm in diameter were also produced by vacuum heating of C-Si film at degrees C: The infrared spectrum showed significant absorption features at 9.
The 21 mu m feature is one of the candidate unidentified infrared bands on the spectra of carbon-rich post-asymptotic giant branch stars. Structure of WO3 ultrafine particles and their characteristic solid states.
Mami Kurumada, Osamu Kido, Takeshi Sato, Hitoshi Suzuki, Yuki Kimura, Katsuya Kamitsuji, Yoshio Saito, Chihiro Kaito.
WO3 nanoparticles from 10 to nm in diameter were formed by burning tungsten wire in low-oxygen-partial-pressure atmosphere in Ar gas. The structure of the nm-order particle was cubic WO3, and for the particle larger than 50 nm, the structure was triclinic WO3. The color of the produced samples changed from blue to yellowish green and yellow depending on the particle size. It was also shown that the present particle is a good transmittance material for mid-IR light with wavelength between 5 and 20 mu m.
The growth of huge particles by coalescence growth in smoke has been discussed. Production of transition metal-doped ZnO nanoparticles by using RF plasma field. Takeshi Sato, Hitoshi Suzuki, Osamu Kido, Mami Kurumada, Katsuya Kamitsuji, Yuki Kimura, Hiromichi Kawasaki, Satoo Kaneko, Yoshio Saito, Chihiro Kaito. Transition metals, such as tungsten W , molybdenum Mo and chromium Cr , were doped into ZnO nanoparticles using an RF plasma system. The resulting ZnO nanoparticles with the size of nm changed from white to yellowish or to orange depending on the doped transition metals.
The doping position of these transition metals in the ZnO crystal was the same as that determined in a previous paper J. Crystal Growth It was found that light with wavelength shorter than nm can be removed by doping. The morphological change due to doping of elements was discussed in terms of the difference of ionicity. Morphological alteration upon phase transition and effects of oxygen impurities of chromium nanoparticles.
Osamu Kido, Katsuya Kamitsuji, Mami Kurumada, Takeshi Sato, Yuki Kimura, Hitoshi Suzuki, Yoshio Saito, Chihiro Kaito. The morphological alteration from delta- to alpha-Cr nanoparticles and the phase transition temperature were directly observed by in situ experiment using a transmission electron microscope.
The icositetrahedral nanoparticle of delta-Cr transformed into a rhombic dodecahedral nanoparticle of alpha-Cr upon heating at degrees C: It was demonstrated that the most stable shape of the alpha-Cr nanoparticle is the rhombic dodecahedron. Upon heating the alpha-Cr nanoparticle at degrees C; the 1 1 3 layer of Cr2O3 grew topotactically in the direction of [] of alpha-Cr nanoparticle. Crystalline Mg2SiO4 and amorphous Mg-bearing silicate grain formation by coalescence and growth.
A novel method for producing MgO and SiO2 smokes was developed. Mg-bearing silicate grain formation using the coalescence and growth of MgO and SiO2 grains was carried out in our laboratory. It becomes evident that single and poly crystalline Mg2SiO4 forsterite and amorphous Mg-bearing silicate grains can be produced by the coalescence and growth of MgO and SiO2 grains.
This result suggests that the observed crystalline Mg2SiO4 grains and amorphous Mg-bearing silicate particles in Red Super Giant RSG , Asymptotic Giant Branch AGB , post-AGB and planetary nebula PNe could be produced by the coalescence and growth of MgO and SiO2 grains.
Transition temperature to crystal phase of Al86Mn14 quasicrystal ultrafine particles determined by direct observation and characterization of surface oxide layer. Al-Mn quasicrystal ultrafine particles can be produced by the advanced gas evaporation method AGEM , which is a method of preparing ultrafine alloy particles by coalescence growth among the particles near the evaporation sources.
We investigated the phase transition temperature from a quasicrystal to a stable crystal, by examining successive electron diffraction patterns of an ultrafine particle in an in situ experiment using a transmission electron microscope. In spite of the report that the Al86Mn14 quasicrystal transforms into the crystal phase at around degreesC on thin film specimens, the quasicrystal ultrafine particle transformed at degreesC, i.
Since the cross-sectional view of the surface oxide layer of the quasicrystal ultrafine particles can be easily observed, the surface oxides of eta-Al2O3 and MnO were characterized as a result of the oxidation of residual atoms on the surface of the produced alloy particles including the quasicrystals.
Direct observation of the formation of alumina phase by metallic Al solid-SiO 2 solid reaction. The formation of Al 2 O 3 phases by the solid-solid reaction of a metallic Al layer evaporated on a SiO 2 amorphous grain has been induced by heating above degrees C in vacuum 1 x 10 -6 Pa. The distortion process of the amorphous SiO 2 grains by the formation of Al 2 O 3 have been directly imaged by in-situ TEM observation.
A partly deposited Al layer covered the SiO 2 grains after heating at degrees C, and gamma-Al 2 O 3 grains of about 25 nm diameters were formed on the SiO 2 surface.
Upon the growth of Al 2 O 3 , the SiO 2 grain decomposed into a mixture of metallic Si and SiO 2 and disappeared as a result of sublimation due to the formation of SiO x at high temperatures.
The present result on dust surface dynamics will become an important field with respect to the metamorphism of grains from the astromineralogical viewpoint. Direct observation of the metamorphism of silicon oxide grains. Experimental studies on the metamorphism of SiO x grains under heating at 10 -6 Pa have been conducted using a high-resolution transmission electron microscope. Si crystallites were predominantly grown at to degreesC in SiO x grains. The Si crystallites disappeared at degreesC and evaporated as the SiO phase.
Growth of diamond from Si-containing amorphous carbon film using synchrotron radiation. Si-doped amorphous carbon film prepared by the simultaneous vacuum evaporation of carbon and silicon has been irradiated by a synchrotron radiation SR beam.
The preferential growth of diamond crystals was found by transmission electron microscope observation conducted after SR irradiation. It was also found that the solid-solution phase of carbon and silicon with the diamond structure was produced in the as-deposited film and at the initial stage of the crystallization. The solid-solution crystal remained in the stable phase up to 6 nm in size.
The catalytic effect of Si was prominent in the growth of diamond. Kido, Y. Higashino, K. Kamitsuji, M. Kurumada, T. Sato, Y.
Kimura, H. Suzuki, Y. Saito, C. The iron oxide ultrafine particles prepared by the gas evaporation method, in which commercial alpha-Fe2O3 powder is evaporated, are composed of alpha-Fe2O3 particles covered with a gamma-Fe2O3 mantle layer.
To study the phase transition temperature of the gamma-Fe2O3 mantle layer, the particles were heated and observed in a transmission electron microscope. The present specimen of gamma-Fe2O3 transformed completely to alpha-Fe2O3 at above degreesC, and this phase transition was irreversible. The phase transition temperature was 1. The growth mechanism of the present specimen of alpha-Fe2O3 particles covered with the gamma-Fe2O3 mantle layer has been discussed in terms of the difference in the cooling rates between the inside and the surface of the particle at around the evaporation source.
Phase transition temperature of gamma-Fe2O3 ultrafine particle. Correlations between crystallite size, shape, surface, and infrared spectra using the Ti-C system.
crystallites less than 10 nm in size showed an absorption feature at This The When the carbide grains were covered with a carbon layer, the absorption peaks were considerably weakened, i. A possible explanation is that the effects of size and shape on the spectra depend on the surface anisotropy. TEM study of early Ni4Ti3 precipitation and R-phase in Ni-rich NiTi nanoparticles.
The structure of NiTi shape memory alloy nanoparticles was determined by high-resolution electron microscopy. Lattice images of an R-phase particle suggested the existence of a Ni-rich Guinier-Preston zone G.
C Acta Materialia Inc. Published by Elsevier Ltd. Growth and structure of Ge clusters produced by Ge-C co-evaporation. Complete mixture films of carbon and germanium produced by the co-evaporation in vacuum were directly heated in a transmission electron microscope.
It was noticed that the diffusion and growth of Ge dots in the mixture film take place at approximately degreesC. On the other hand, Ge dots coated with amorphous carbon were produced by simultaneous evaporation of carbon and Ge in Ar gas at 10 kPa. In addition to Ge clusters of nm in size, multiple-twin Ge clusters with the size of 10 nm have been produced in carbon soot.
サンスポ 株式会社産経デジタル. ねとらぼエンタ アイティメディア株式会社. Asagei Biz 株式会社徳間書店. Sponichi Annex スポーツニッポン新聞社. モデルプレス 年1月17日. ORICON NEWS. oricon ME 年3月29日.
モデルプレス 年2月5日. モデルプレス 年7月20日. ザテレビジョン 年10月22日. 株式会社 デイリースポーツ. 株式会社 oricon ME. ABEMA TIMES. 株式会社 AbemaTV. RIZAP 株式会社. ORICON NEWS 年11月23日. マイナビニュース 年11月4日. バラエティ復帰の道は？ – YouTube （しくじり先生 俺みたいになるな!! VIAF 1 WorldCat（VIAF経由）. カテゴリ : 日本の女性モデル 日本の女性ファッションモデル 日本の女性タレント グラビアアイドル エイジアプロモーション 日本の女性YouTuber フィリピン系日本人 スペイン系日本人 横浜市出身の人物 年生 存命人物. 隠しカテゴリ: ウィキデータにない公式ウェブサイト VIAF識別子が指定されている記事 NDL識別子が指定されている記事 WorldCat-VIAF識別子が指定されている記事 ISBNマジックリンクを使用しているページ.
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木村 ゆうき
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木村有希 (モデル) – Wikipedia
Its formation processes have been 村木 on the basis of knowledge obtained under the 1 G /3389.txt on Earth and is thus not fully /13615.txt under realistic conditions. The insights gained may have significant implications in areas that 木村 ゆうき on the production of protein crystals, such as structural biology, pharmacy, and biophysics, and for 木村 ゆうき fundamental understanding of crystallization mechanisms. Furthermore, the lower 木村 ゆうき of crystallinity observed in silicates formed in outflows of lower mass-loss-rate stars might be caused by the formation of magnesium silicide ゆきう this relatively hydrogen-rich environment. Miura, T. Furthermore, by optical measurement. Chihiro Kaito, Shinichi Sasaki, Yu Miyazaki, Akihito Kumamoto, Mami Kurumada, 木村 ゆうき Yokoyama, Midori Saito, Yuki Kimura, Hitoshi Suzuki.