The Ginger-shaped Asteroid 4179 Toutatis: New Observations from a Successful Flyby of Chang'e-2

On 13 December 2012, Chang'e-2 conducted a successful flyby of the near-Earth asteroid 4179 Toutatis at a closest distance of 770 $\pm$ 120 meters from the asteroid's surface. The highest-resolution image, with a resolution of better than 3 meters, reveals new discoveries on the asteroid, e.g., a giant basin at the big end, a sharply perpendicular silhouette near the neck region, and direct evidence of boulders and regolith, which suggests that Toutatis may bear a rubble-pile structure. Toutatis' maximum physical length and width are (4.75 $\times$ 1.95 km) $\pm$10$\%$, respectively, and the direction of the +$z$ axis is estimated to be (250$\pm$5$^\circ$, 63$\pm$5$^\circ$) with respect to the J2000 ecliptic coordinate system. The bifurcated configuration is indicative of a contact binary origin for Toutatis, which is composed of two lobes (head and body). Chang'e-2 observations have significantly improved our understanding of the characteristics, formation, and evolution of asteroids in general.Comment: 21 pages, 3 figures, 1 tabl

Coupling of material point and continuum discontinuum element methods for simulating blast-induced fractures in rock

A rock blasting simulation method is proposed that couples the material point method (MPM) and continuum discontinuum element method (CDEM). Blast-induced rock fractures are captured by the CDEM using normal and shear springs, and the explosive detonation is simulated by the MPM with a Jones-Wilkins-Lee equation of state. A particle-surface/edge contact method is introduced into the MPM-CDEM to calculate the interaction between the detonation products and rock medium. Three numerical examples are presented to verify the effectiveness of the proposed method. The fracture degree is represented as the ratio of the number of fractured springs to the total number of springs, and is used to analyze the evolution of shear and tension cracks under blasting. The simulation results show that the proposed numerical method well simulates blast-induced rock fractures and considers both progressive rock fracturing and the real explosive detonation. In particular, the expansion of the detonation gas, crushed zone around the blasthole, radial cracks, and effects of pre-existing stress on the blast-induced fractures are all successfully simulated

OsGL1-3 is Involved in Cuticular Wax Biosynthesis and Tolerance to Water Deficit in Rice

<div><p>Cuticular wax covers aerial organs of plants and functions as the outermost barrier against non-stomatal water loss. We reported here the functional characterization of the Glossy1(GL1)-homologous gene <i>OsGL1-3</i> in rice using overexpression and RNAi transgenic rice plants. <i>OsGL1-3</i> gene was ubiquitously expressed at different level in rice plants except root and its expression was up-regulated under ABA and PEG treatments. The transient expression of OsGL1-3–GFP fusion protein indicated that OsGL1-3 is mainly localized in the plasma membrane. Compared to the wild type, overexpression rice plants exhibited stunted growth, more wax crystallization on leaf surface, and significantly increased total cuticular wax load due to the prominent changes of C₃₀–C₃₂ aldehydes and C₃₀ primary alcohols. While the RNAi knockdown mutant of <i>OsGL1-3</i> exhibited no significant difference in plant height, but less wax crystallization and decreased total cuticular wax accumulation on leaf surface. All these evidences, together with the effects of <i>OsGL1-3</i> on the expression of some wax synthesis related genes, suggest that OsGL1-3 is involved in cuticular wax biosynthesis. Overexpression of <i>OsGL1-3</i> decreased chlorophyll leaching and water loss rate whereas increased tolerance to water deficit at both seedling and late-tillering stages, suggesting an important role of <i>OsGL1-3</i> in drought tolerance.</p></div

Cuticular permeability and membrane integrity assays of OE3, Ri1 and WT.

<p>A, Chlorophyll leaching assays with matured leaves of OE3, Ri1 and WT, immersed in 80% ethanol for different time intervals. B, Water-loss rate of detached leaves of OE3, Ri1 and WT. C, Electrolyte leakage assays with matured leaves of OE3, Ri1 and WT under water deficit treatment. D, MDA content comparison of OE3, Ri1 and WT leaves under water deficit treatment. Data are shown by mean ± SE with three replicates.</p

Phenological and agronomic data for OE3, Ri1 and WT plants growing under irrigated conditions.

<p>The results show averages of three replicates, and error bars indicate ± SD.</p

Cuticular wax amount and composition in leaves and sheaths of OE3, Ri1 and WT rice plants.

<p>Rice leaves and sheaths of late-tillering stage in WT (cv. <i>Nipponbare</i>), OE3 and Ri1 plants grown in soil were used for analysis of cuticular wax compositions and loads. The results show averages of three replicates, and error bars indicate ± SD. A, Cuticular wax composition and loads in the leaves of OE3 and Ri1 plants compared to WT. B, Cuticular wax composition and loads in the sheaths of OE3 and Ri1 plants compared to WT. C, Cuticular wax components amount and total cuticular wax amount in the leaves of OE3 and Ri1 plants compared to WT. D, Cuticular wax components amount and total cuticular wax amount in the sheaths of OE3 and Ri1 plants compared to WT. E, Cuticular wax compositional analysis in carbons length from C₂₀ to C₃₄ in the leaves of OE3 and Ri1 plants compared to WT. F, Cuticular wax compositional analysis in carbons length from C₂₀ to C₃₄ in the sheaths of OE3 and Ri1 plants compared to WT.</p

Spacial and stress-responsive expression of <i>OsGL1-3</i>.

<p>A, Semiquantative RT–PCR analysis of <i>OsGL1-3</i> in root, culm, shoot, leaf, sheath, panicle and germinating seed of Nipponbare. B, Semiquantative RT–PCR analysis of the <i>OsGL1-3</i> expression in Nipponbare at 4-leaf stage after heat, cold, PEG, ABA or NaCl treatments. <i>OsActin1</i> gene was used as a control and the numbers in brackets indicate the number of PCR cycles.</p