The role of sticky interstellar organic material in the formation of asteroids

Abstract— Collision experiments and measurements of viscoelastic properties were performed involving an interstellar organic material analogue to investigate the growth of organic grains in the protosolar nebula. The organic material was found to be stickiest at a radius of between 2.3 and 3.0 AU, with a maximum sticking velocity of 5 m s^?1 for millimeter‐size organic grains. This stickiness is considered to have resulted in the very rapid coagulation of organic grain aggregates and subsequent formation of planetesimals in the early stage of the turbulent accretion disk. The planetesimals formed in this region appear to be represent achondrite parent bodies. In contrast, the formation of planetesimals at <2.1 and >3.0 AU begins with the establishment of a passive disk because silicate and ice grains are not as sticky as organic grains.     

A 60-year record of rainfall from the sediments of Jinheung Pond,Jeongeup, Korea

This paper describes mean grain-size data from the ¹³⁷Cs- and ²¹⁰Pb-dated sediment core BS-3 (33-cm long) recovered from Jinheung Pond, located in the southwestern part of the Korean Peninsula. Grain-size analysis of the Jinheung Pond sediments shows a clear signal for changes in annual precipitation over the past 60 years. Instrumental records of annual precipitation (AP) and the annual summation of the precipitation of >50 mm per day (AP50), which reflects the energy available for sediment transport, correlate well with the mean grain-size distributions measured in the core. The most plausible mechanism for this response in mean grain size is variations in the annual amount and intensity of precipitation. Heavy precipitation enhances soil erosion over the catchment area and increases the transport capacity of streams and rivers. Thus, coarser mean grain size should reflect higher precipitation, and smaller mean grain size should reflect lower rainfall. In the data from core BS-3, however, grain-size peaks attributed to increased annual precipitation are not prominent. This is because a dam prevents removal of fine particles from the pond via the outflow. Therefore, the mean grain-size value represents somewhat larger sediments together with fine clays. The results of this study show that sediments of dammed lakes and ponds are well suited for high-resolution environmental investigations, especially for records of changes in precipitation over time.     

Solar Wind Speed and Expansion Rate of the Coronal Magnetic Field in Solar Maximum and Minimum Phases

Relationships between solar wind speed and expansion rate of the coronal magnetic field have been studied mainly by in-ecliptic observations of artificial satellites and some off-ecliptic data by Ulysses. In this paper, we use the solar wind speed estimated by interplanetary scintillation (IPS) observations in the whole heliosphere. Two synoptic maps of SWS estimated by IPS observations are constructed for two Carrington rotations CR 1830 and 1901; CR 1830 starting on the 11th of June, 1990 is in the maximum phase of solar activity cycle and CR 1901 starting on the 29th of September, 1995 is in the minimum phase. Each of the maps consist of 64800 (360×180) data points. Similar synoptic maps of expansion rate of the coronal magnetic field (RBR) calculated by the so-called potential model are also constructed under a radial field assumption for CR 1830 and CR1901. Highly significant correlation (r=–0.66) is found between the SWS and the RBR during CR1901 in the solar minimum phase; that is, high-speed winds emanate from photospheric areas corresponding to low expansion rate of the coronal magnetic field and low speed winds emanate from photospheric areas of high expansion rate. A similar result is found during CR 1830 in solar maximum phase, though the correlation is relatively low (r=–0.29). The correlation is improved when both the data during CR 1830 and CR 1901 are used together; the correlation coefficient becomes –0.67 in this case. These results suggest that the correlation analysis between the SWS and the RBR can be applied to estimate the solar wind speed from the expansion rate of the coronal magnetic field, though the correlation between them may depend on the solar activity cycle. We need further study of correlation analysis for the entire solar cycle to get an accurate empirical equation for the estimation of solar wind speed. If the solar wind speed is estimated successfully by an empirical equation, it can be used as an initial condition of a solar wind model for space weather forecasts.     

Full‐scale shaking table test of a base‐isolated medical facility subjected to vertical motions

Base isolation is a well known technology that has been proven to reduce structural response to horizontal ground accelerations. However, vertical response still remains a topic of concern for base‐isolated buildings, perhaps more so than in fixed‐base buildings as isolation is often used when high performance is required. To investigate the effects of vertical response on building contents and nonstructural components, a series of full‐scale shaking table tests were conducted at the E‐Defense facility in Japan. A four‐story base‐isolated reinforced concrete building was outfitted as a medical facility with a wide variety of contents, and the behavior of the contents was observed. The rubber base isolation system was found to significantly amplify vertical accelerations in some cases. However, the damage caused by the vertical ground motions was not detrimental when peak vertical floor accelerations remained below 2 g with three exceptions: (1) small items placed on shelves slid or toppled; (2) objects jumped when placed on nonrigid furniture, which tended to increase the response; and (3) equipment with vertical eccentricities rocked and jumped. In these tests, all equipment and nonstructural components remained functional after shaking. Copyright © 2013 John Wiley & Sons, Ltd.     

Uranium and Thorium Isotope Distribution in an Offshore Bottom Sediment Core of the Selenga Delta, Lake Baikal, Siberia

Distribution of uranium and thorium isotopes in a short sediment core obtained offshore of the Selenga Delta in Lake Baikal, Siberia, was investigated to establish their sedimentary behaviors and to look for a linkage to paleoenvironmental changes. The sediments were composed of dominantly fine detrital materials (70–85%) and a relatively high sedimentation rate (ca. 0.03 cm y⁻¹). The depth profile of ²³⁸U content in bulk sediment samples showed a large variation of 70–123 Bq kg⁻¹, while ²³²Th profile showed a relatively narrow range from 36 to 56 Bq kg⁻¹. The observed ²³⁴U/²³⁸U activity ratios revealed a marked disequilibrium ranging from 1.53 to 1.84 with a mean value of 1.71 ± 0.07, demonstrating the presence of 50–80% authigenic ²³⁸U in the bulk sediments. The distribution of this authigenic ²³⁸U did not display any clear correlation with variations in sediment composition (organic, carbonate, Bio-SiO₂ and mineral contents) including grain size median. The profile of terrigenous ²³⁸U showed a relatively similar pattern to that of ²³²Th. Results of sequential leaching indicate that ²³⁸U in Fe–Mn oxyhydroxides fractions were responsible for the distribution of authigenic ²³⁸U rather than in Bio-SiO₂ fraction. The distribution of authigenic ²³⁸U in the bottom sediments may be explained by the fluctuation of U adsorption capacity on particles including organic matter and Fe–Mn oxyhydroxides before they entered the lake. This study highlights the potential use of authigenic and terrigenous U (Th) signatures in sediments to trace the behavior of U (Th) and to reconstruct environmental (e.g., hydrological) changes in the lake catchment area.     

Production of the Blood Pressure Lowing Peptides from Brown Alga （ Undaria pinnatifida ）

Brown alga （ Undaria pinnatifida） was treated with alginate lyase and hydrolyzed using 17 kinds of proteases and the inhibitory activity of the hydrolysates for the angiotensin-I-converting enzyme （ACE） was measured. Four hydrolysates with potent ACE-inhibitory activity were administered singly and orally to spontaneously hypertensive rats （SHRs）. The systolic blood pressure of SHRs decreases significantly after single oral administration of the brown alga hydrolysates by pro- tease S ＇ Amano＇ （from Bacillus stearothermophilus） at the concentration of 10 （mg protein） （kg body weight）^ - 1. In the 17 weeks of feeding experiment, 7-week-old SHRs were fed standard diet supplemented with the brown alga hydrolysates for 10 weeks. In SHRs fed 1.0 and 0.1% brown alga hydrolysates, elevating of systolic bloodpressure was significantly suppressed for 7 weeks. To elucidate the active components, the brown alga hydrolysates were fractionated by 1-butanol extraction and HPLC on a reverse-phase column. Seven kinds of ACE-inhibitory peptides were isolated and identified by amino acid composition analysis, sequence analysis, and LC-MS with the results Val-Tyr, Ile-Tyr, Ala-Trp, Phe-Tyr, Val-Trp, Ile-Trp, and Leu-Trp. Each peptide was determined to have an antihypertensive effect after a single oral administration in SHRs. The brown alga hydrolysates were also confirmed to decrease the blood pressure in humans.     

The assessment of weathering stages in granites using an EC/pH meter

The sidewall effects of a wind tunnel on aeolian sand transport were investigated experimentally. A wind tunnel was used to conduct the experiments with a given channel height of 120 cm and varying widths (B) of 40, 60, 80, 100 and 120 cm. Both vertical profiles of wind velocity and sand mass flux were measured at different locations across the test section. The results show that the wind velocity with saltation first increases and then decreases to a minimum, from the sidewall to the central line of the wind tunnel. The discrepancy among wind velocities at different locations of the transverse section decreases with decreasing tunnel width. The wind friction velocity across the wind tunnel floor, with the exception of the region closest to the sidewalls, does not deviate strongly in wide wind tunnels from that along the central line, whereas it does vary in narrow tunnels. The sand mass fluxes, with the exception of some near-bed regions, are larger along the central line of the wind tunnel than they are at the quarter width location from the sidewall. Unlikely previously reported results, the dimensionless sand transport rate, Qg / (ρu³) (where Q is the total sand transport rate, g is the gravitational acceleration constant, ρ is the air density, and u is the wind friction velocity), first decreases and then increases with the dimensionless friction velocity, u / u_t (where u_t is the threshold friction velocity). The above differences may be attributed to the sidewall effects of the wind tunnel. A dimensionless parameter, F_B = u / (gB)^1/2, is defined to reflect the sidewall effects on aeolian sand transport. The flows with F_B of 0.33 or less may be free from the sidewall effects of the wind tunnel and can ensure accurate saltation tunnel simulation.     

Orbit of periodic comet 153P/Ikeya–Zhang

The orbit of Comet C/2002C1 (Ikeya–Zhang) has a similarity to that of Comet C/1661C1 (Hevelius), and the numerical integration of the motion of C/2002C1 backward shows a possible linkage of those two comets. Thus, 153P/Ikeya–Zhang was designated a periodic comet. Historical records of comets in 877 and 1273 are also identified with Comet 153P/Ikeya–Zhang. The integrated orbital elements during 77 and 2362, and historical records of the comet are also presented and discussed.     

Some instabilities in the 3/1 and 2/1 resonances

In a very simple way, it is possible to show the existence of small regions of instability, inside the observed 3/1 and 2/1 Kirkwood Gap, by using the classical Laplace-Lagrange secular theory.     

The dust distribution in some smallHII regions

Based on the calibrated maps in the Hα andV bands, simple shell models for the distributions of ionized gas and dust are calculated for the smallHii regions S237 and S254–S257. In deriving the dust distribution from theV-band maps, it is assumed that scattering particles are made of dirty ice. The results of calculation show that a dust depletion zone should be placed in the central region of each of the observedHii regions. The formation of this dust depletion zone and the evolutionary state of theseHii regions are briefly discussed.