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Organic matter found in early Martian sediment1-4 may help in defining early Martian environmental conditions and provide the key to understanding Mars’ prebiotic chemistry and habitability. However, the origin of this organic matter remains uncertain. Anomalous 13C depletion was recently discovered in this organic matter5, and has the potential to elucidate their origins, though plausible mechanism to cause the strong 13C depletion is unknown. Here, we present experimental and theoretical studies which demonstrated that solar ultraviolet photolysis of CO2 yields strongly 13C-depleted CO. In a reducing atmosphere, isotopically anomalous CO is converted into organic molecules that are deposited into sediments. Therefore, atmospheric synthesis of organics from CO is a plausible mechanism to explain the presence of organics in early Martian sediments and its strong 13C depletion. Furthermore, this mechanism could explain 13C enrichment of early Martian CO2 without the aid of long-term carbon escape into space. A mass balance model calculation using the estimated isotopic fractionation factor indicated approximately 20% conversion of volcanic CO2 into organics via CO, which satisfied the available data for carbon isotopes. Consequently, our results suggest that considerable amounts of organic matter may have been synthesized in a reducing early Martian atmosphere and stored within sediment.

Flowing water and brine have been proposed to cause seasonally reappearing dark streaks called recurring slope lineae (RSL) on steep warm slopes on Mars, along with other formation mechanisms that do not involve water. This study aims to examine whether the evaporation of water vapor from the RSL, whether from fresh water or brine, is detectable by observing water vapor and/or clouds. In this study, we summarize the possible rate and duration of water-vapor emission from RSL in different scenarios, simulate how the emitted water vapor behaves in a global climate model, and discuss the detectability of water vapor in nadir observations during existing and future explorations. We found that, in typical cases, rapid horizontal dissipation within the planetary boundary layer (PBL) following the release of water vapor prohibits cloud formation and the excess water vapor from being distinguished from the background with existing observations. Thus, we conclude that the lack of correlation between the RSL activities and the overlying water-vapor column density does not necessarily rule out the wet origin of RSL. Nevertheless, we also found that water vapor tends to accumulate in basins and valleys in some cases due to the combined effects of topography and low PBL; we suggest the locations of such configuration as targets for future atmospheric studies of Mars dedicated to quantifying water-vapor release (associated with RSL) to elucidate the formation mechanism(s) of the RSL on the planet., 52 pages, 15 figures, accepted for publication in Icarus. Supplementary movies will become available from the journal

Martian atmospheric neon (Ne) has been detected by Viking and also found as trapped gas in Martian meteorites, though its abundance and isotopic composition have not been well determined. Because the timescale of Ne loss via atmospheric escape estimated from recent measurements with MAVEN is short (0.6--1 $\times$ 10$^8$ years), the abundance and isotope composition of Martian atmospheric Ne reflect recent atmospheric gas supply mostly from volcanic degassing. Thus, it can serve as a probe for the volatile content of the interior. Here we show that the tentatively-informed atmospheric Ne abundance suggests recent active volcanism and the mantle being richer in Ne than Earth's mantle today by more than a factor of 5--80. The estimated mantle Ne abundance requires efficient solar nebular gas capture or accretion of Ne-rich materials such as solar-wind-implanted dust in the planet formation stage, both of which provide important constraints on the abundance of other volatile elements in the interior and the accretion history of Mars. More precise determination of atmospheric Ne abundance and isotopic composition by in situ analysis or Mars sample return is crucial for distinguishing the possible origins of Ne., Comment: 57 pages, 4 figures, accepted for publication in Icarus

Earth's surface environment is largely influenced by its budget of major volatile elements: carbon (C), nitrogen (N), and hydrogen (H). Although the volatiles on Earth are thought to have been delivered by chondritic materials, the elemental composition of the bulk silicate Earth (BSE) shows depletion in the order of N, C, and H. Previous studies have concluded that non-chondritic materials are needed for this depletion pattern. Here, we model the evolution of the volatile abundances in the atmosphere, oceans, crust, mantle, and core through the accretion history by considering elemental partitioning and impact erosion. We show that the BSE depletion pattern can be reproduced from continuous accretion of chondritic bodies by the partitioning of C into the core and H storage in the magma ocean in the main accretion stage and atmospheric erosion of N in the late accretion stage. This scenario requires a relatively oxidized magma ocean ($\log_{10} f_{\rm O_2}$ $\gtrsim$ $\rm{IW}$$-2$, where $f_{\rm O_2}$ is the oxygen fugacity, ${\rm IW}$ is $\log_{10} f_{\rm O_2}^{\rm IW}$, and $f_{\rm O_2}^{\rm IW}$ is $f_{\rm O_2}$ at the iron-w\"{u}stite buffer), the dominance of small impactors in the late accretion, and the storage of H and C in oceanic water and carbonates in the late accretion stage, all of which are naturally expected from the formation of an Earth-sized planet in the habitable zone., Comment: 17 pages, 4 figures (comprising 11 panels in total), 1 table, Methods, and Supplementary Information (available online: https://www.nature.com/articles/s41598-021-99240-w)

We model nitrogen (N) partitioning in the magma ocean stage and cycling between the surface and mantle through Earth's history, and suggest that N in the present-day mantle may be set by subduction before the development of the modern N cycle. Introduction: On present-day Earth, N cycling between the surface and mantle is largely controlled by biological N fixation and aerobic biological processing. Biological N fixation brings the majority of inorganic N into the modern N cycle. In the oceans, dissolved nitrate is the main form of nitrogen available for life, and dissimilatory denitrification leads to residual nitrate being kinetically enriched in 15N by ~6‰. The isotopically enriched nitrate is then reduced to ammonium and finally trapped in sediments (e.g., Stüeken al. 2016). Though secular subduction of 15N-rich sediments should cause 15N enrichment in the mantle, the mantle N sampled from mid-ocean ridge basalt (MORB) is rather depleted in 15N (~-5‰), which is known as the N isotopic disequilibrium. Previous studies hypothesized that N in the mantle is a primordial component (Cartingy & Marty, 2013; Labidi et al. 2020). In the primordial origin scenario, the isotopic disequilibrium is attributed to atmospheric escape, which enriched the atmosphere with 15N. Another study proposed a recycling origin scenario in which the N isotopic composition of sediments has changed over time (Marty & Dauphas, 2003). Neither of these scenarios has been modeled quantitatively. Here we test the different scenarios by using numerical models coupled with N isotopes. Methods: We developed two sets of models for the origin of observed mantle N isotopic composition: i) the primordial origin and ii) the recycling origin. The results are either accepted or rejected by the comparison to the amounts and isotopic compositions of N in contemporary surface reservoirs and mantle (Johnson & Goldblatt, 2015; Labidi et al. 2020). For the primordial origin scenario, we calculate N partitioning between the atmosphere and mantle upon magma ocean solidification by using a melt-trapping model (Hier-Majumder & Hirschmann, 2017) and the partitioning coefficients between minerals, silicate melt, and the atmosphere (Li et al. 2013; Dalou et al. 2017). We consider the range of oxygen fugacity relevant to Earth's formation. We also estimate the 15N-enrichment effect due to EUV-driven escape (Watson et al. 1981) and solar-wind pick-up (Lichtenegger et al. 2010) to see how much atmospheric N should be removed to reproduce ~+5‰ difference between the atmosphere and mantle. For the recycling origin scenario, we calculate secular N exchange between the surface reservoirs and mantle. Our model is based on that of Labidi et al. (2020). The isotopic fractionation between the atmosphere and subducting sediments is taken to be ~-9‰ and ~+6‰ before and after the Great Oxidation Event at 2.4 Ga, respectively, considering the change from abiotic fixation and anaerobic processing to biological fixation and aerobic processing. We fix the subduction and degassing fluxes on present-day Earth, and their power-law indices as a function of time as parameters. Bulk N partitioning and the isotopic difference between the reservoirs in the initial state are also treated as parameters. Figure 1: Nitrogen partitioning between the atmosphere and mantle at the time of magma ocean solidification (PAN = present-day atmospheric nitrogen). The range of the modeled mantle N content reflects the uncertainty in the oxygen fugacity of the magma ocean. Figure 2: Evolution of masses (left) and 15N/14N ratios (right) in the surface reservoirs (blue) and mantle (red). Curves show accepted models having different initial conditions and fluxes. Gray areas are the estimates for present-day surface reservoirs and mantle. Results: Because N is relatively insoluble in silicate melts, it is mostly partitioned into the atmosphere even when trapping in interstitial melts is considered (Figure 1). Partitioning N into the mantle as much as present-day leads to 100 times excess in PAL N. We found that the excess amount of N can be removed neither by EUV- nor solar-wind-induced loss without excessive 15N enrichment in the atmosphere. Impact erosion by the late veneer bombardment removes atmospheric N without isotopic fractionation up to ~10 bar (Sakuraba et al. 2019), but it may not be sufficient to remove all excess N in the atmosphere. Since the results of our partitioning model suggest that the primordial origin is unlikely, next we tested the recycling scenario in our N cycling model (Figure 2). In our successful runs, the mantle is initially depleted in N, and N in the present-day mantle is a result of higher net subduction flux on early Earth where sedimentary N is depleted in 15N due to abiotic N fixation and anaerobic N processing. The change to modern N cycle is visible in the kink in δ15N evolution, which may provide a way to test our model with evidence from geologic record. Discussion: We suggest that N partitioning between the surface and deep Earth may be set by subduction driven by plate tectonics and partially by biology. This also suggests that the difference of atmospheric N contents between Venus and Earth, the former of which has three times more N in the atmosphere, is caused by their long-term evolution rather than early formation and differentiation processes. Conclusions: We conclude that N in the present-day mantle may be set by subduction before the development of the modern N cycle. Further results for parameter survey and discussion on other geological and geochemical constraints will be shown in our presentation.

Mars' liquid water might not have been lost to space as thought

Here we discuss the current state of knowledge on how atmospheric escape processes can fractionate noble gas isotopes and moderately volatile rock-forming elements that populate primordial atmospheres, magma ocean related environments, and catastrophically outgassed steam atmospheres. Variations of isotopes and volatile elements in different planetary reservoirs keep information about atmospheric escape, composition and even the source of accreting material. We summarize our knowledge on atmospheric isotope ratios and discuss the latest evidence that proto-Venus and Earth captured small H$_2$-dominated primordial atmospheres that were lost by EUV-driven hydrodynamic escape after the disk dispersed. All relevant thermal and non-thermal atmospheric escape processes that can fractionate various isotopes and volatile elements are discussed. Erosion of early atmospheres, crust and mantle by large planetary impactors are also addressed. Further, we discuss how moderately volatile elements such as the radioactive heat producing element $^{40}$K and other rock-forming elements such as Mg can also be outgassed and lost from magma oceans that originate on large planetary embryos and accreting planets. Outgassed elements escape from planetary embryos with masses that are $\geq$\,M$_{\rm Moon}$ directly, or due to hydrodynamic drag of escaping H atoms originating from primordial- or steam atmospheres at more massive embryos. We discuss how these processes affect the final elemental composition and ratios such as K/U, Fe/Mg of early planets and their building blocks. Finally, we review modeling efforts that constrain the early evolution of Venus, Earth and Mars by reproducing their measured present day atmospheric $^{36}$Ar/$^{38}$Ar, $^{20}$Ne/$^{22}$Ne noble gas isotope ratios and the role of isotopes on the loss of water and its connection to the redox state on early Mars., Comment: 65 pages, 17 figures. This is a preprint of an article published in Space Science Reviews. The final authenticated version can be found online at: https://doi.org/10.1007/s11214-020-00701-x

The hydrogen isotopic (D/H) ratio reflects the global cycling and evolution of water on Earth as it fractionates through planetary processes. We model the water cycle taking seafloor hydrothermal alteration, chemical alteration of continental crust, slab subduction, hydrogen escape from the early Earth, and degassing at mid-ocean ridges, hot spots, and arcs into account. The differences in D/H ratios between present-day oceans, oceanic and continental crust, and mantle are thought to reflect isotopic fractionation through seafloor alteration, chemical alteration, and slab dehydration. However, if the speed of plate tectonics has been nearly constant through out Earth's history, the degassing and regassing rates are too small to reach the present-day D/H ratios. We show that (a) hydrogen escape from reduced early atmosphere, (b) secular net regassing, or (c) faster plate tectonics on early Earth is needed to reproduce the present-day D/H ratios of the water reservoirs. The low D/H ratio of Archean seawater at 3.8 Ga has previously been interpreted as a signature of (a) hydrogen escape, but we find it can also be explained either by (b) secular net regassing or by (c) faster plate tectonics on early Earth. The rates of hydrogen escape from early Earth and secular regassing on present-day Earth are constrained to be lower than 2.1 x 10^11 kg/yr and 3.9 x 10^11 kg/yr. Consequently, the volume of water in the present-day mantle could result entirely from the regassing through Earth's history. In that case, the volume of initial oceans could be 2 to 3 times larger than that of current Earth. We suggest that, in addition to the D/H ratio of Archean seawater, identifying the D/H ratios of both seawater and mantle throughout Earth's history would allow to distinguish these evolutionary scenarios., Comment: 35 pages, 9 figures, accepted for publication in EPSL

Context. Pebble accretion is among the major theories of planet formation. Aerodynamically small particles, called pebbles, are highly affected by the gas flow. A growing planet embedded in a protoplanetary disk induces three-dimensional (3D) gas flow. In our previous work, Paper I, we focused on the shear regime of pebble accretion and investigated the influence of planet-induced gas flow on pebble accretion. In Paper I, we found that pebble accretion is inefficient in the planet-induced gas flow compared to that of the unperturbed flow, particularly when St ≲ 10−3, where St is the Stokes number. Aims. Following on the findings of Paper I, we investigate the influence of planet-induced gas flow on pebble accretion. We did not consider the headwind of the gas in Paper I. Here, we extend our study to the headwind regime of pebble accretion. Methods. Assuming a nonisothermal, inviscid sub-Keplerian gas disk, we performed 3D hydrodynamical simulations on the spherical polar grid hosting a planet with the dimensionless mass, m = RBondi∕H, located at its center, where RBondi and H are the Bondi radius and the disk scale height, respectively. We then numerically integrated the equation of motion for pebbles in 3D using hydrodynamical simulation data. Results. We first divided the planet-induced gas flow into two regimes: flow-shear and flow-headwind. In the flow-shear regime, where the planet-induced gas flow has a vertically rotational symmetric structure, we find that the outcome is identical to what we obtained in Paper I. In the flow-headwind regime, the strong headwind of the gas breaks the symmetric structure of the planet-induced gas flow. In the flow-headwind regime, we find that the trajectories of pebbles with St ≲ 10−3 in the planet-induced gas flow differ significantly from those of the unperturbed flow. The recycling flow, where gas from the disk enters the gravitational sphere at low latitudes and exits at high latitudes, gathers pebbles around the planet. We derive the flow transition mass analytically, mt, flow, which discriminates between the flow-headwind and flow-shear regimes. From the relation between m, mt, flow and mt, peb, where mt, peb is the transition mass of the accretion regime of pebbles, we classify the results obtained in both Paper I and this study into four groups. In particular, only when the Stokes gas drag law is adopted and m < min(mt, peb, mt, flow), where the accretion and flow regime are both in the headwind regime, the accretion probability of pebbles with St ≲ 10−3 is enhanced in the planet-induced gas flow compared to that of the unperturbed flow. Conclusions. Combining our results with the spacial variety of turbulence strength and pebble size in a disk, we conclude that the planet-induced gas flow still allows for pebble accretion in the early stage of planet formation. The suppression of pebble accretion due to the planet-induced gas flow occurs only in the late stage of planet formation, more specifically, in the inner region of the disk. This may be helpful for explaining the distribution of exoplanets and the architecture of the Solar System, both of which have small inner and large outer planets.

Copyright © 2016 by The Geochemical Society of Japan. water runoff in the Noachian period (e.g., Hynek et al., 2010; Di Achille and Hynek, 2010). Moreover, the Hesperian outflow channels suggest a large total volume of water (e.g., Carr and Head, 2015). The current reservoir of surface water occurs mainly as polar layered deposits (PLD), although the total volume of this reservoir is significantly smaller than the estimated volume of the Paleo-oceans (e.g., Kurokawa et al., 2014). An increasing amount of evidence obtained by the Mars Odyssey Gamma Ray Spectrometer (Boynton et al., 2002, 2007) and the Mars Express radar sounder (Mouginot et al., 2012) suggests the presence of additional reservoirs of water in the form of ground ice at middle to high latitudes. The presence of recurring slope lineae (McEwen et al., 2014) in a wide range of regions including low-latitudes implies that water exchange is ongoing between the atmosphere and the underground cryosphere. Interactive evolution of multiple water-ice reservoirs on Mars: Insights from hydrogen isotope compositions

The first milk substitute for giant panda cubs was developed in 1988 based on limited data about giant panda breast milk and that of certain types of bear. Mixtures of other formulas have also been fed to cubs at some facilities. However, they are not of sufficient nutritional quality for promoting growth in panda cubs. Here, we report analysis of giant panda breast milk and propose new milk substitutes for cubs, which were developed based on the results of our analysis. The Chengdu Research Base of Giant Panda Breeding obtained breast milk samples from three giant pandas. Up to 30 ml of breast milk were collected from each mother by hand. Then, the milk samples were frozen and sent to Nihon University. The levels of protein, fat, carbohydrates, ash, moisture, vitamins, minerals, total amino acids, fatty acids, lactose and other carbohydrates in the milk were analyzed. The breast milk samples exhibited the following nutritional values: protein: 6.6-8.5%, fat: 6.9-16.4%, carbohydrates: 2.5-9.1%, ash: 0.9-1.0% and moisture: 67-83%. We designed two kinds of milk substitutes based on the data obtained and the nutritional requirements of dogs, cats and rodents. The nutritional composition of the milk substitutes for the first and second stages was as follows: protein: 38 and 26%, fat: 40 and 40%, carbohydrates: 13 and 25%, ash: 6 and 6% and moisture: 3 and 3%, respectively. In addition, the substitutes contained vitamins, minerals, taurine, docosahexaenoic acid, lactoferrin, nucleotides and other nutrients.

The ubiquity of super-Earths poses a problem for planet formation theory to explain how they avoided becoming gas giants. Rapid recycling of the envelope gas of planets embedded in a protoplanetary disc has been proposed to delay the cooling and following accretion of disc gas. We compare isothermal and non-isothermal 3D hydrodynamical simulations of the gas flow past a planet to investigate the influence on the feasibility of the recycling mechanism. Radiative cooling is implemented by using the beta cooling model. We find that, in either case, gas enters the Bondi sphere at high latitudes and leaves through the midplane regions, or vice versa when disc gas rotates sub-Keplerian. However, in contrast to the isothermal case where the recycling flow reaches the deeper part of the envelope, the inflow is inhibited from reaching the deep envelope in the non-isothermal case. Once the atmosphere starts cooling, buoyant force prevents the high-entropy disc gas from intruding the low-entropy atmosphere. We suggest that the buoyancy barrier isolates the lower envelope from the recycling and allows further cooling, which may lead runaway gas accretion onto the core., 15 pages, 11 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

The atmospheres of the terrestrial planets are known to have been modified as a consequence of the impact degassing and atmospheric erosion during the late accretion. Despite the commonality of these processes, there are distinct gaps -- roughly two orders of magnitude -- between the abundances of noble gases and nitrogen in the present-day atmospheres on Venus, Earth, and Mars. The element partitioning on planetary surfaces is thought to be significantly different between the three planets ~4 Ga: the runaway greenhouse on Venus, the carbon-silicate cycle and ocean formation on Earth, and the CO2-ice and H2O-ice formation on Mars. Consequences of element partitioning for the atmospheric evolution during the late accretion onto Venus, Earth, and Mars are investigated with a numerical model. We set upper limits to the partial pressures of CO2 and H2O on Earth and Mars, which corresponds to the state of phase equilibrium and carbon-silicate cycle. The final N2 mass shrinks by ~40% and ~15% for Earth and Mars, respectively. The effect of element partitioning is found to be insufficient to reproduce the gaps. For Venus, the survival of the primordial atmosphere through the late accretion may partially account for the present-day atmosphere. Whereas on Mars, the atmospheric escape due to solar extreme UV and wind may have also influenced the atmospheric evolution., 31 pages, 12 Figures, accepted for publication in Icarus

We examine the history of the loss and replenishment of the Martian atmosphere using elemental and isotopic compositions of nitrogen and noble gases. The evolution of the atmosphere is calculated by taking into consideration various processes: impact erosion and replenishment by asteroids and comets, atmospheric escape induced by solar radiation and wind, volcanic degassing, and gas deposition by interplanetary dust particles. Our model reproduces the elemental and isotopic compositions of N and noble gases (except for Xe) in the Martian atmosphere, as inferred from exploration missions and analyses of Martian meteorites. Other processes such as ionization-induced fractionation, which are not included in our model, are likely to make a large contribution in producing the current Xe isotope composition. Since intense impacts during the heavy bombardment period greatly affect the atmospheric mass, the atmospheric pressure evolves stochastically. Whereas a dense atmosphere preserves primitive isotopic compositions, a thin atmosphere on early Mars is severely influenced by stochastic impact events and following escape-induced fractionation. The onset of fractionation following the decrease in atmospheric pressure is explained by shorter timescales of isotopic fractionation under a lower atmospheric pressure. The comparison of our numerical results with the less fractionated N ($^15$N/$^14$N) and Ar ($^38$Ar/$^36$Ar) isotope compositions of the ancient atmosphere recorded in the Martian meteorite Allan Hills 84001 provides a lower limit of the atmospheric pressure in 4 Ga to preserve the primitive isotopic compositions. We conclude that the atmospheric pressure was higher than approximately 0.5 bar at 4 Ga., Accepted for Publication in Icarus (54 pages, 16 figures)

The limit of the planetary radiation (longwave radiation) of a planet with oceans on its surface is determined by various mechanisms called “radiation limits,” which can be classified as the Komabayashi–Ingersoll limit and the radiation limit of the troposphere. The effects of atmospheric absorption of the incoming central star radiation (shortwave radiation) on the radiation limit of the troposphere are investigated. To clarify the effects, simple parameterization of the absorption is performed. Two cases are found using an atmospheric model without a window for the longwave radiation. When the absorption in the upper atmosphere is effective, the radiation limit becomes larger than in the no-absorption case. On the other hand, the radiation limit disappears in the absence of a window for the incoming radiation.

Observations have revealed that a significant number of hot Jupiters have anomalously large radii. Layered convection induced by compositional inhomogeneity has been proposed to account for the radius anomaly of hot Jupiters. To reexamine the impact of the compositional inhomogeneity, we perform an evolutionary calculation by determining convection regime at each evolutionary time step according to the criteria from linear analyses. It is shown that the impact is limited in the case of the monotonic gradient of heavy element abundance. The layered convection is absent for the first 1 Gyr from the formation of hot Jupiters and instead overturning convection develops. The super-adiabaticity of the temperature gradient is limited by the neutrally stable state for the Ledoux stability criterion. The effect of the increased mass of heavy elements essentially compensates the effect of the delayed contraction on the planetary radius caused by compositional inhomogeneity. In addition, even in the case where the layered convection is artificially imposed, this mechanism requires extremely thin layers (~ 10^1-10^3 cm) to account for the observed radius anomaly. The long-term stability of such thin layers remains to be studied. Therefore, if the criteria adopted in this paper are adequate, it might be difficult to explain the inflated radii of hot Jupiters by monotonic gradient of heavy element abundance alone., Comment: 31 pages, 9 figures, accepted for publication in ApJ

Martian surface morphology implies that Mars was once warm enough to maintain persistent liquid water on its surface. While the high D/H ratios (~6 times the Earth's ocean water) of the current martian atmosphere suggest that significant water has been lost from the surface during martian history, the timing, processes, and the amount of the water loss have been poorly constrained. Recent technical developments of ion-microprobe analysis of martian meteorites have provided accurate estimation of hydrogen isotope compositions (D/H) of martian water reservoirs at the time when the meteorites formed. Based on the D/H data from the meteorites, this study demonstrates that the water loss during the pre-Noachian (>41-99 m global equivalent layers, GEL) was more significant than in the rest of martian history (>10-53 m GEL). Combining our results with geological and geomorphological evidence for ancient oceans, we propose that undetected subsurface water/ice (~100-1000 m GEL) should have existed, and it exceeds the observable present water inventory (~20-30 m GEL) on Mars., 29 pages, 4 figures, 2 tables, accepted for publication in Earth and Planetary Science Letters

Metallurgically bonded transition joints which enable to connect reprocessing equipments made of superior corrosion resisitant valve metals (Ti-5Ta, Zr or Ti) to stainless steel piping are required for nuclear fuel reprocessing plants. The authors have developed dissimilar transition joints made of stainless steel and Ti-5Ta, Zr or Ti with an insert metal of Ta by the hot bond rolling process of clad bars and clad pipes, using a newly developed mill called “rotary reduction mill”.This report presents the manufacturing process of dissimilar transition joints produced from the clad pipe with three layers by the hot bond rolling. First, the method of hot bond rolling of clad pipe is proposed. Then, the mechanical and corrosion properties of the dissimilar transition joints are evaluated in detail by carrying out various tests. Finally, the rolling properties in the clad pipe method are discussed.

Short-period exoplanets potentially lose envelope masses during their evolution because of atmospheric escape caused by the intense XUV radiation from their host stars. We develop a combined model of atmospheric mass loss calculation and thermal evolution calculation of a planet to simulate its evolution and explore the dependences on the formation history of the planet. Thermal atmospheric escape as well as the Roche-lobe overflow contributes to mass loss. The maximum initial planetary model mass depends primarily on the assumed evolution model of the stellar XUV luminosity. We adapt the model to CoRoT-7b and Kepler-10b to explore the evolution of both planets and the maximum initial mass of these planets. We take the recent X-ray observation of CoRoT-7 into account and exploring the effect of different XUV evolution models on the planetary initial mass. Our calculations indicate that both hot super Earths could be remnants of Jupiter mass gas planets., 7 pages, 7 figures, accepted for publication in MNRAS

Scanning tunneling microscopy (STM) images of Pt ultrafine particles dispersed on a thin aluminum oxide film were obtained for the first time. The Pt/Al2O3 model catalyst consists of aluminum oxide prepared by vacuum-depositing aluminum metal on a native-oxide-covered single crystal silicon surface and air-oxidized, and Pt metal particles vacuum-deposited on this alumina surface. The mechanism of STM imaging for this system was investigated.

Fresh surgical specimens from 14 oral cancer patients were used for chemosensitivity tests by MTT assay.The chemosensitivity of 11 out of 19 samples taken from the patients was able to be assessed. The mean optical density (OD) of the control culture containing no drugs was 0.163, which was suitable for measuring the fine sensitivity of cells against various anti-cancer drugs. Squamous cell carcinomas (SCC) were highly sensitive to cisplatin (CDDP), followed by peplomycin (PEP) and 5-fluorouracil (5-FU).Synergistic growth inhibitory effect was detected against 2 SCC when PEP was used in combination with small amounts of CDDP. Thus, MTT assay was considered to be a useful chemosensitivity screening test for oral cancers.

Macrocycles consisted of pyridine rings and acetylene bonds were prepared by Eglinton coupling from a tandem precursor bearing two terminal alkynyl groups. The composition of molecular size in the cyclized products changed by the reaction solvent. In pyridine, 9-meric and bigger macrocycles were obtained, while that of 6-mer was not. On the other hand, in pyridine/THF mixed solvent, the 6-mer was obtained as a major product.

A macrocyclic host molecule having pyridine-pyridone-pyridine modules for saccharide recognition was prepared by Cu(II)-mediated oxidative homocoupling of a tandem diethynyl precursor. In CH(2)Cl(2), the host molecule associated with dodecyl β-maltoside much more strongly (K(a) = 1.4 × 10(6) M(-1)) than with octyl monohexosides (K(a) = ca. 2 × 10(3) to 1 × 10(4) M(-1)), accompanied with induced CDs. An all-pyridine macrocyclic host was also studied, and its binding strength with saccharides was weaker than that for the pyridine-pyridone-pyridine host.

Luminescence and excitation energy transfer of the J-aggregate of cyanine dyes: 5,6,5',6'-dibenzo-1,1'-diethyl-2,2'-cyanine chloride (dye I), 5,5'-dichloro-3,3'-diethyl-9-phenyl-thiacarbocyanine chloride (dye II), 3,3'-dimethyl-9-phenyl-4,5,4',5'-naphthothiacarbocyanine chloride (dye III), 1,1'-diethyl-2,2'-cyanine iodide (dye IV), in the monolayer assemblies have been studied. Sensitization of resonance fluorescence of the acceptor aggregate (dyes II and III) by the donor aggregate (dyes I and IV) is evident in the mixed assemblies, donor: acceptor, which contain two kinds of the J-aggregates in the same layer plane. The dependence of sensitization efficiency on the composition of the dye I: dye II assembly has been interpreted in terms of an empirical Perrin relation. The slope of the Perrin type plot of sensitized fluorescence is consistent with the model that the dye I aggregate and the dye II aggregate are distributed at random in the layer plane as if each of them were a large supermolecule.

Natural killer (NK) cell activity of OK-432-stimulated peripheral blood mononuclear cells (PBMC) was examined. Low concentrations of exogenously added recombinant interleukin 2 (rIL-2) were able to augment OK-432-induced NK cell activity. This kind of augmenting effect depended on the dose of rIL-2 and manifested itself only in PBMC stimulated with OK-432 (OK-MC) followed by rIL-2; augmentation did not happen when drugs were applied in the reverse order.The existence of CD16+ /CD25+ (IL-2 receptor positive; IL-2R+) and CD57+ /CD25+ double positive cells which possess NK cell surface markers in OK-MC markedly increased in a long-term culture (12 days). A strong positive correlation was observed between the IL-2-dependent augmentation of NK activity and the quantitative changes in cell populations that possessed NK cell phenotypes. Furthermore, this augmenting effect was detectable within 4 h after addition of rIL-2 at single cell level, suggesting that the effect did not require NK cell's DNA synthesis.Thus, the use of OK-432 activated NK cells in combination with IL-2 in clinical trials is expected to afford high efficiency in cancer immunotherapy.

Macrocycles consisted of pyridine rings and acetylene bonds were prepared by Eglinton coupling from a tandem precursor bearing two terminal alkynyl groups. The composition of molecular size in the cyclized products changed by the reaction solvent. In pyridine, 9-meric and bigger macrocycles were obtained, while that of 6-mer was not. On the other hand, in pyridine/THF mixed solvent, the 6-mer was obtained as a major product.

Antitumor activities of OK-432-stimulated peripheral blood mononuclear cells (PBMC) were examined. Killer activity against natural killer (NK) cell-sensitive K562 as well as lymphokine activated killer (LAK) cell-sensitive Daudi and PC3 target cells were detected among PBMC cultured with a low dose (0.0125-0.05 KE/ml) of OK-432. Kinetic analysis of killer activity showed that it reached a plateau level by 48 h of culture. Various freshly isolated tumor cells from oral cancer patients were also lysed by both the autologous and allogeneic OK-432-stimulated PBMC (OK-MC), suggesting that the specificity of the killer was not restricted by HLA and was thus non-specific. Fluorescence activated cell sortor (FACS) analyses showed that CD57+/CD25+ and CD16+/CD25+ cells were increased in PBMC after 48-h stimulation with OK-432. The killer activity was further augmented by the addition of rIL-2 at the time of killer assay.Tumor growth inhibitory factor (TGIF) activity, which we previously reported, was found in the culture supernatant (CSN) of OK-MC from various cancer patients. The titer of TGIF from these patients was high enough, 16-64 × of the reciprocal dilution of the CSN, which was almost equivalent to the activity from normal healthy controls.These results suggest that two kinds of antitumor activities were induced in the OK-432-stimulated PBMC in vitro, the one being cell-mediated and the other lymphokine-mediated (TGIF). OK-MC is thus supposed to be effective for adoptive immunotherapy (AIT) in oral cancer patients.

IPTV (Internet Protocol Television) terminals have a large receiving buffer for IP networks with large delay jitter. However the large buffer for jitter would cause large delay in playout. In this paper, we propose novel methods to achieve low-delay playout for IPTV terminals even in large-jitter networks. To minimize buffering time of received data in an IPTV terminal, the buffering time should be the same amount as the maximum jitter only when the lowest delayed data is received. Under above condition, we determine the time of starting playout by utilizing only the lowest delayed data. Also, in order to keep low-delay playout, we control playout clock using the maximum occupancy of the receive buffer. Compared with other solutions proposed earlier to address network delay jitter, our proposal is focused particularly on providing features including low delay playout, applicability to large delay jitter, adjustment of processing workload (low processing cost), safe control without buffer underflow, and resilience against discontinuous packet loss.

Malignant tumor consisting of elk, r. cells is often seen in the kidney and several other organs. This tumor, however, rarely occurs in oral and, maxillofacial regions. We recently experienced a huge clear cell carcinoma in a 79-year-old female, which putatively originated in the mandible, and o expansile into the right maxilla. zygoma, temporal bone, orbital, and partially into the cranium. Lymphnode (LN) metastasis was observed in the right submandibular LN.Histopathologically, the tumor was primarily composed of large sheets and islands of uniform vacuolated and clear cells separated by a mature fibrous connetive tissue. The tumor contained no glandular epithelial cells or myoepithelial cells. PAS positive and diastase digestable granules were observed in a small number of tumor cells.Immunohistochemical examination revealed that the tumor cells focally showed positive reaction to keratin (KT) and epithelial membrane antigen (EMA), but completely negative for actin, S-100, vimentin, and myosin.Ultrastructurally, the tumor cells were characterized by the presence of abundant cytoplasm and lack of intracellular organelles. Tonofilaments and desmosomes were, however, occasionally observed. From all of these findings, it is considered that the tumor cell may be derived from the odontogenic epithelium and mimick to clear cell odontogenic tumor.More interestingly, it was found that the tumor partially showed squamous cell differentiation after chemotherapy and immunotherapy. It is likely that the clear cell tumor may transform into squamous cell during differentiation process or vice versa, or the tumor may initially consist of two different kinds of tumor cells.The histogenesis of the tumor and its potential possiblility to differentiate into squamous epithelium are discussed.

Recently the laser doppler velocimeter has been developped as aids in evaluation of microcircuratory flow in a variety of human tissue. We have used this instrument to measure viability of the flaps which were transplanted to the reconstruction of maxillo-facial region.The blood circulation of D-P flaps and Abbe flap were measured by laser doppler verocimeter. The analog data of the blood circulation was analyzed by using personal computer. The software for data analysis was developped by ourselves.The laser doppler verocimeter is a non-invasive instrument capable of instantaneous and continuous evalation of local flow in tissue microcirculation. It is fit to monitor viability of flaps used oral and maxillo-facial surgery.

LB films and liposomes incorporating J-aggregates of two kinds of cyanine dyes at the same membrane surface have been prepared. Four cyanine dyes, 1,1′-diethyl-2,2′-cyanine chloride or iodide (dye-I), 5,6,5′,6′-dibenzo-1,1′-diethyl-2,2′-cyanine chloride (dye-II), 5,5′-dichloro-3,3′-diethyl-9-phenylthiacarbocyanine chloride (dye-III), 3,3′-dimethyl-9-phenyl-4,5,4′,5′-naphthothiacarbocyanine chloride (dye-IV) were employed. In the case of a couple of dye-II:dye-III aggregates, quenching of resonance fluorescence of dye-II aggregate and sensitization of resonance fluorescence of dye-III aggregate, due to excitation energy transfer, were observed. The energy transfer also occurs in the dye-I:dye-III, dye-I:dye-IV, dye-II:dye-IV aggregates. In these cases, quinocyanine dye (dye-I, dye-II) aggregates and thiacarbocyanine dye (dye-III, dye-IV) aggregates act as the energy donor and acceptor, respectively.